Develop Bugs

Device recognized in ADB but not in fastboot

Trying to unlock bootloader on my pixel 2 XL. Using a windows 10 64-bit laptop, usb-c cable that came with the phone, latest drivers and up to date platform tools. Debugging enabled. OEM unlock enabled.
Phone is recognized in ADB just fine. "Adb devices" results in the the device being listed. "ADB reboot bootloader" reboots the phone into fastboot mode just fine. Once in fastboot mode, however, "fastboot devices" yields nothing.
Pulling my hair out here, and not much hair left to pull. I suspect I'm going to have to tinker with the computer's security settings to get the drivers to install correctly. Any thoughts?

I seem to remember the same thing happening when I got mine a couple days ago and unlocked the BL within a few hours of unboxing. I ended up doing the standard unlock followed by unlock critical commands anyway. Worked fine for me.

morrowa2 said:
Trying to unlock bootloader on my pixel 2 XL. Using a windows 10 64-bit laptop, usb-c cable that came with the phone, latest drivers and up to date platform tools. Debugging enabled. OEM unlock enabled.
Phone is recognized in ADB just fine. "Adb devices" results in the the device being listed. "ADB reboot bootloader" reboots the phone into fastboot mode just fine. Once in fastboot mode, however, "fastboot devices" yields nothing.
Pulling my hair out here, and not much hair left to pull. I suspect I'm going to have to tinker with the computer's security settings to get the drivers to install correctly. Any thoughts?
Click to expand...
Click to collapse
Try just turning the phone off and then entering fastboot via volume down and power button. THEN, plus in your phone. Do a 'fastboot devices' and see if it shows up now. In my experience, I got my phone...checked oem unlock and all that...booted into fastboot mode via hard method. And my phone is detected instantly. I did not install any drivers, update platform tools (mine is from like 2012), and even used a third-party USB-C cable. It works every time. Also, I am using the adb and fastboot executables from an older adb minimal set. Probably from like a year or so ago. I don't ever use the SDK ones really anymore.

morrowa2 said:
Trying to unlock bootloader on my pixel 2 XL. Using a windows 10 64-bit laptop, usb-c cable that came with the phone, latest drivers and up to date platform tools. Debugging enabled. OEM unlock enabled.
Phone is recognized in ADB just fine. "Adb devices" results in the the device being listed. "ADB reboot bootloader" reboots the phone into fastboot mode just fine. Once in fastboot mode, however, "fastboot devices" yields nothing.
Pulling my hair out here, and not much hair left to pull. I suspect I'm going to have to tinker with the computer's security settings to get the drivers to install correctly. Any thoughts?
Click to expand...
Click to collapse
I'd check and make sure your adb/fastboot is up to date, or do a reinstall just in case.

There are so many options for adb/fastboot and drivers. Where does one find "the latest," that everyone is speaking of?

Thanks for the suggestions but still not working. Even tried disabling driver signature verification at startup. I'm going to uninstall everything, factory reset the device and start over. Might also try a usb-c to usb-a cable. Any other thoughts?
Update: Nothing worked until I used a usb-c to usb-a cable, then it worked like a charm. Must be a Lenovo thing.

morrowa2 said:
Thanks for the suggestions but still not working. Even tried disabling driver signature verification at startup. I'm going to uninstall everything, factory reset the device and start over. Might also try a usb-c to usb-a cable. Any other thoughts?
Update: Nothing worked until I used a usb-c to usb-a cable, then it worked like a charm. Must be a Lenovo thing.
Click to expand...
Click to collapse
I can't even get adb to recognize my device ....I have used multiple cables I'm about to return this phone

canemaxx said:
I can't even get adb to recognize my device ....I have used multiple cables I'm about to return this phone
Click to expand...
Click to collapse
have you tried a usb-c to usb-a cable. that worked for me.

morrowa2 said:
There are so many options for adb/fastboot and drivers. Where does one find "the latest," that everyone is speaking of?
Click to expand...
Click to collapse
Latest ADB/fastboot: https://developer.android.com/studio/releases/platform-tools.html
Latest USB driver: https://developer.android.com/studio/run/win-usb.html

I had no luck except about once in 20 it'd work. Then swapped to a different USB-C port on my laptop, then it worked. FWIW, I tried USB-C to USB-C and USB-C --> USB-A (adapter) to USB-C and it didn't make a difference.

js042507 said:
Try just turning the phone off and then entering fastboot via volume down and power button. THEN, plus in your phone. Do a 'fastboot devices' and see if it shows up now. In my experience, I got my phone...checked oem unlock and all that...booted into fastboot mode via hard method. And my phone is detected instantly. I did not install any drivers, update platform tools (mine is from like 2012), and even used a third-party USB-C cable. It works every time. Also, I am using the adb and fastboot executables from an older adb minimal set. Probably from like a year or so ago. I don't ever use the SDK ones really anymore.
Click to expand...
Click to collapse
I did this and when in the bootloader screen, I am able to display fastboot devices, but when I go into recovery mode and try and flash something via ADB (the November patch since I am not pulling it OTA), it seems to start but it just sits at "Verifying update package" on the phone and "loading: 'taimen-ota-******.zip'" and never progresses. Almost like the PC and the phone are not talking properly?

tluley51 said:
I did this and when in the bootloader screen, I am able to display fastboot devices, but when I go into recovery mode and try and flash something via ADB (the November patch since I am not pulling it OTA), it seems to start but it just sits at "Verifying update package" on the phone and "loading: 'taimen-ota-******.zip'" and never progresses. Almost like the PC and the phone are not talking properly?
Click to expand...
Click to collapse
Like others have stated, maybe try a USB-C to regular USB-A cable. I have only used that type of cable, but didn't realize that the actual cable that comes with the phone might be a problem. I never used it to test that theory though.

js042507 said:
Like others have stated, maybe try a USB-C to regular USB-A cable. I have only used that type of cable, but didn't realize that the actual cable that comes with the phone might be a problem. I never used it to test that theory though.
Click to expand...
Click to collapse
Yeah that is all I have ever used. I use a USB A to C Cable Matters cable.

tluley51 said:
Yeah that is all I have ever used. I use a USB A to C Cable Matters cable.
Click to expand...
Click to collapse
I don't know then. I haven't attempted the update yet to provide any feedback. However, others have reported this issue in the 'November OTA' thread. I would look there.

morrowa2 said:
Trying to unlock bootloader on my pixel 2 XL. Using a windows 10 64-bit laptop, usb-c cable that came with the phone, latest drivers and up to date platform tools. Debugging enabled. OEM unlock enabled.
Phone is recognized in ADB just fine. "Adb devices" results in the the device being listed. "ADB reboot bootloader" reboots the phone into fastboot mode just fine. Once in fastboot mode, however, "fastboot devices" yields nothing.
Pulling my hair out here, and not much hair left to pull. I suspect I'm going to have to tinker with the computer's security settings to get the drivers to install correctly. Any thoughts?
Click to expand...
Click to collapse
For anyone in the future, ensure the that Device Manager is showing the 'Android Composite ADB Interface' driver installed.
Then, just download the latest Platform Tools (from https://developer.android.com/studio/releases/platform-tools), and from inside that folder, open a Powershell prompt, and then 'adb reboot bootloader'. Once you are in the 'fastboot' mode, the 'fastboot devices' command works.

I had the same problem. I fixed it by plugging in my UBS-C to USB-A cable into a USB 3 port instead of a USB 2 port.

I am facing the same issue, its been almost 20 days. Tried everything but couldn't get it worked. So dropped the idea of rooting my px2L

My issue was I needed to replace the drivers for fastboot mode (ADB was fine). There are two drivers, one for each mode.
fastboot doesn't see device
I've read a lot of articles about this problem but I can't resolve it. I decided to install my developer application on phone using wifi. To do this I need to do some things with my phone. The firs...
android.stackexchange.com

cooltime said:
My issue was I needed to replace the drivers for fastboot mode (ADB was fine). There are two drivers, one for each mode.
fastboot doesn't see device
I've read a lot of articles about this problem but I can't resolve it. I decided to install my developer application on phone using wifi. To do this I need to do some things with my phone. The firs...
android.stackexchange.com
Click to expand...
Click to collapse
worked for me thanks.

cooltime said:
My issue was I needed to replace the drivers for fastboot mode (ADB was fine). There are two drivers, one for each mode.
fastboot doesn't see device
I've read a lot of articles about this problem but I can't resolve it. I decided to install my developer application on phone using wifi. To do this I need to do some things with my phone. The firs...
android.stackexchange.com
Click to expand...
Click to collapse
This works... Get the Google Driver.

Feb 2019 update kills PC usb connection

Strange issue. After applying the Feb 2019 security patch over air, my phone is no longer recognizing when it is plugged into a PC. I plug into my PC and I get a charge symbol on my battery but no pull down option to switch from charging to USB mode. Things I've tried:
1. New Cable although the wife has a Pixel 3 (standard) that works with this cable and computer just fine.
2. Different PC
3. Toggling USB debugging
4. Changing the USB setting in developer mode to transfer
5. When I plug a USB stick into the phone using the USB-C to USB-A adapter, the phone recognizes the stick and I can browse files
6. "Cleaning" the USB-C port
7. Also booted into safe mode (which I would assume should be like a factory reset) but no USB.
8. Switched between USB 3 and USB 2 ports on the PC.
It seems to me that there's a software issue with the Feb update that messed with the usb settings. I called google and they just want me to factory reset my device before they will transfer me to tech support. I'm avoiding that because I don't want to go back through the time/trouble of resetting up my phone. Any tips/tricks I've missed here?

If you have a Google variant with the BL unlocked, flash the factory image with the -w removed from the flash-all batch file. That way, you won't lose data. If you are on the Verizon variant or don't want to unlock you BL, sideload the OTA from stock recovery. See if it cleans up your issue. Also, sounds like you might have a driver issue on your PC. Easier to fix that first if it is the issue.

I have the February update over the air and I had no issues connecting to my Chromebook (crouton) via USB to pull an APK with ADB. I did have to turn USB debugging back on (not sure if I turned it off or if it was turned off from an update) and change the connection type, it was set to charging only.

More info this morning. I have an Android based car stereo that when I plugged my phone into this morning, I did get the USB drop down. So it seems to be a windows 10 problem. I have both a Surface pro 4 and a desktop running windows 10 that are fully up to date that show the same symptoms. I don't know how I'm going to sideload an update if I can't connect it to my computer.
1. What I don't understand is why the Pixel 3 would work and the Pixel 3 XL would not. Same driver set, no?
2. Also, PC with Windows 7 also has same issue.

copekyle said:
More info this morning. I have an Android based car stereo that when I plugged my phone into this morning, I did get the USB drop down. So it seems to be a windows 10 problem. I have both a Surface pro 4 and a desktop running windows 10 that are fully up to date that show the same symptoms. I don't know how I'm going to sideload an update if I can't connect it to my computer.
1. What I don't understand is why the Pixel 3 would work and the Pixel 3 XL would not. Same driver set, no?
2. Also, PC with Windows 7 also has same issue.
Click to expand...
Click to collapse
Try putting the phone into Fastboot mode and use the command "fastboot devices" to see if it is recognized. If it is, then the problem is on the ADB side, which is part of the Android system.
If it can connect via Fastboot, it's less likely to be a driver issue. You can try "adb devices" too with the phone booted to see if it is recognizing it all. May need to toggle through the various connection modes, I believe I used PTP the last time, but not certain.
As for sideloading, you will need the phone to be recognized by either ADB or Fastboot. You can sideload an OTA update from Recovery with a locked bootloader or as @sliding_billy said you can unlock the bootloader and flash the factory image which is done via Fastboot.
I would also verify that you have the latest version of the Android SDK installed just to cover that base.

copekyle said:
More info this morning. I have an Android based car stereo that when I plugged my phone into this morning, I did get the USB drop down. So it seems to be a windows 10 problem. I have both a Surface pro 4 and a desktop running windows 10 that are fully up to date that show the same symptoms. I don't know how I'm going to sideload an update if I can't connect it to my computer.
1. What I don't understand is why the Pixel 3 would work and the Pixel 3 XL would not. Same driver set, no?
2. Also, PC with Windows 7 also has same issue.
Click to expand...
Click to collapse
You don't need to be in file transfer mode to connect via fastboot. Check connection from there after using the combo keys to get into fastboot (power/vol down) for the factory image or one step further into recovery for sideload.

Neither Fastboot devices or ADB devices lists a device. When put in fastboot and recovery, my device manager on either computer does not register that there is a device connected.

copekyle said:
Neither Fastboot devices or ADB devices lists a device. When put in fastboot and recovery, my device manager on either computer does not register that there is a device connected.
Click to expand...
Click to collapse
Sounds like you have attempted everything... New cable (but rereading I don't see where you tried using a C>A cable instead of a C>C and that definitely needs tried). New computer/port/OS. Direct connect to fastboot. I think you are going to need to backup to the cloud (at least you have a functional device with internet) and factory reset the device.
P.S. I just thought about this, but do you have the current platform tools (ADB/Fastboot)? https://developer.android.com/studio/releases/platform-tools.html

sliding_billy said:
Sounds like you have attempted everything... New cable (but rereading I don't see where you tried using a C>A cable instead of a C>C and that definitely needs tried). New computer/port/OS. Direct connect to fastboot. I think you are going to need to backup to the cloud (at least you have a functional device with internet) and factory reset the device.
P.S. I just thought about this, but do you have the current platform tools (ADB/Fastboot)? https://developer.android.com/studio/releases/platform-tools.html
Click to expand...
Click to collapse
Sadly I don't have a computer with a USB C port. I have been using only cables with C>A. I downloaded the latest platform tools yesterday before trying fastboot/adb. I'm waiting for a call back from Google tier 2 tech support within 72 hours. If anything comes of it, I will report back here.

copekyle said:
Sadly I don't have a computer with a USB C port. I have been using only cables with C>A. I downloaded the latest platform tools yesterday before trying fastboot/adb. I'm waiting for a call back from Google tier 2 tech support within 72 hours. If anything comes of it, I will report back here.
Click to expand...
Click to collapse
Good luck!

[solved] Recover Data: Touchscreen doesn't respond, fastboot only, Stock Android One

Hey gals and guys,
my girlfriend dropped her Xiaomi A2 lite and no the touchscreen doesn't respond. The phone has the stock Android One and I can only access fastboot.
Code:
fastboot devices
recognizes the phone.
The recovery is the stock recovery.
Code:
adb devices
won't recognize the phone and gives me an empty line as output
I also can't access the phone via usb with my filebrowser. If I try, the phone makes a "bing"-sound and the filebrowser gives me:
Code:
unable to open MTP device
I am using archlinux and I also have a windows device available.
Is there any chance on getting pictures etc from the phone?
Any suggestions besides getting a replacement for the touchscreen?
Thank you so much.

Connecting via USB probably needs you to click something.
I'm guessing developer mode is not enabled...
If you've got a micro USB OTG cable, you could plug a mouse in.
If you boot TWRP (fastboot boot twrp-3.3.1-dees-troy.img) you should be able to get adb and usb transfers working. Don't need to install it, just boot it. Not sure if that works without unlocked bootloader.

If you've got a micro USB OTG cable, you could plug a mouse in.
Click to expand...
Click to collapse
This did the trick.
Thank you

Phone is detected by "adb devices" but not detected by "fastboot devices"

Phone is detected by "adb devices" but not detected by "fastboot devices"
I purchased a used P3a XL from Swappa. I would like to install a custom ROM. As we all know, in order for me to do that I need to unlock the bootloader. I think the phone is a Google Edition (checked SKU on box against what is sold in stores).
I have done quite a bit of research before posting here and think I have the process correct. I have enabled developer mode and toggled the OEM unlock option. I am able to "adb devices" and see the phone on my computer terminal. I "adb reboot bootloader" and the phone reboots in to "Fastboot Mode". When I do "fastboot devices" nothing shows. When I boot in to fastbootd (via stock recovery) and execute "fastboot devices" I can see the phone. I execute "fastboot flashing unlock" and it fails with "fastboot flashing unlock failed remote: unrecognized command flashing unlock".
I have tried this on my PixelBook with Linux installed and on my Ubuntu lab machine. Both of those machines give me the same results. I tried with my Windows 10 laptop, but the phone isn't detected by any of my USB-C to USB-A cables.
I have factory wiped the phone a few times and attempted the steps above, but it results in the same thing. Phone is not detected in fastboot. Interestingly, I am able to sideload the latest OTA (QQ3A.200605.001, Jun 2020) without any errors. After sideloading the latest OTA, I am still unable to unlock the bootloader.
I suspect one of two things:
1. The phone is a VZW/Sprint/T-Mo edition. Even so, VZW edition can be unlocked. I tried that method (found an XDA thread to do that).
2. Something is wonky with the phone (bootloader software)
Unfortunately, since I bought it second hand, I do not think Google would honor the hardware warranty to issue me an RMA.
What do you folks think may be an issue?

ruhrohs said:
I purchased a used P3a XL from Swappa. I would like to install a custom ROM. As we all know, in order for me to do that I need to unlock the bootloader. I think the phone is a Google Edition (checked SKU on box against what is sold in stores).
I have done quite a bit of research before posting here and think I have the process correct. I have enabled developer mode and toggled the OEM unlock option. I am able to "adb devices" and see the phone on my computer terminal. I "adb reboot bootloader" and the phone reboots in to "Fastboot Mode". When I do "fastboot devices" nothing shows. When I boot in to fastbootd (via stock recovery) and execute "fastboot devices" I can see the phone. I execute "fastboot flashing unlock" and it fails with "fastboot flashing unlock failed remote: unrecognized command flashing unlock".
I have tried this on my PixelBook with Linux installed and on my Ubuntu lab machine. Both of those machines give me the same results. I tried with my Windows 10 laptop, but the phone isn't detected by any of my USB-C to USB-A cables.
I have factory wiped the phone a few times and attempted the steps above, but it results in the same thing. Phone is not detected in fastboot. Interestingly, I am able to sideload the latest OTA (QQ3A.200605.001, Jun 2020) without any errors. After sideloading the latest OTA, I am still unable to unlock the bootloader.
I suspect one of two things:
1. The phone is a VZW/Sprint/T-Mo edition. Even so, VZW edition can be unlocked. I tried that method (found an XDA thread to do that).
2. Something is wonky with the phone (bootloader software)
Unfortunately, since I bought it second hand, I do not think Google would honor the hardware warranty to issue me an RMA.
What do you folks think may be an issue?
Click to expand...
Click to collapse
Sideloading is an adb function, not fastboot. Make sure you have the lastest Android platform tools. This doesn't mean you can unlock the bootloader but to get fastboot working.

Also make sure you have the oem cable or at least a decent cable, and use a 2.0 port if possible. I've seen other a/b devices refuse to work or give half commands with 3.0+ ports. What does it says underneath oem unlocking in dev settings? I've attached the latest adb/fastboot files just in case you might need them.

Tulsadiver said:
Sideloading is an adb function, not fastboot. Make sure you have the lastest Android platform tools. This doesn't mean you can unlock the bootloader but to get fastboot working.
Click to expand...
Click to collapse
I just updated my Ubuntu machine with the lastest SDK, so both ADB and Fastboot were updated. The phone can be seen with "adb devices". It can be seen with "fastboot devices", but only if the phone is in fastbootd mode. Wouldn't this confirm that fastboot works on the laptop?
41rw4lk said:
Also make sure you have the oem cable or at least a decent cable, and use a 2.0 port if possible. I've seen other a/b devices refuse to work or give half commands with 3.0+ ports. What does it says underneath oem unlocking in dev settings? I've attached the latest adb/fastboot files just in case you might need them.
Click to expand...
Click to collapse
I am using a PixelBook with the original USB-C to USB-C cable that came with the phone. My Windows laptop doesn't see the phone at all
OEM unlock option is enabled.

ruhrohs said:
I just updated my Ubuntu machine with the lastest SDK, so both ADB and Fastboot were updated. The phone can be seen with "adb devices". It can be seen with "fastboot devices", but only if the phone is in fastbootd mode. Wouldn't this confirm that fastboot works on the laptop?
I am using a PixelBook with the original USB-C to USB-C cable that came with the phone. My Windows laptop doesn't see the phone at all
OEM unlock option is enabled.
Click to expand...
Click to collapse
As far as your window laptop, you might try installing usb drivers.
https://developer.android.com/studio/run/win-usb

Tulsadiver said:
As far as your window laptop, you might try installing usb drivers.
https://developer.android.com/studio/run/win-usb
Click to expand...
Click to collapse
Yup, tried that as well. I even went as far as wiping one of my lab machines, installed Windows 7, copied and installed the command line tools only from here: https://developer.android.com/studio#downloads, but no dice. For Windows, I think it's a cable issue. I'm getting new USB-C to USB-A cables delivered tomorrow. Once I get them, I will try on my Windows laptop.

Update to my issue...
Bought a 3 pack of Anker cables. Plugged each of them to my phone and to each of my Win 7 and Win 10 laptops. Both laptops are able to charge the phone, however the don't detect the phone for data transfer/USB debugging. I checked device manager, deleted/uninstalled all Android devices that were listed (including my first generation Pixel XL), rebooted my laptops and tried again. No dice... At this point, I'm chalking it up to the Pixel 3a XL phone itself and an issue with the hardware.
Note to self... Buy a brand new phone for an extra $100 and I would have saved myself over 4 days of troubleshooting an issue.

ruhrohs said:
Update to my issue...
Bought a 3 pack of Anker cables. Plugged each of them to my phone and to each of my Win 7 and Win 10 laptops. Both laptops are able to charge the phone, however the don't detect the phone for data transfer/USB debugging. I checked device manager, deleted/uninstalled all Android devices that were listed (including my first generation Pixel XL), rebooted my laptops and tried again. No dice... At this point, I'm chalking it up to the Pixel 3a XL phone itself and an issue with the hardware.
Note to self... Buy a brand new phone for an extra $100 and I would have saved myself over 4 days of troubleshooting an issue.
Click to expand...
Click to collapse
You do realise that you've got to change the USB settings for it to do data transfer right???

thatsupnow said:
You do realise that you've got to change the USB settings for it to do data transfer right???
Click to expand...
Click to collapse
my problem more than once, ashamed to say. after updating drivers and cords. then forgot to pull my notifications down for that last little line. it's a learning process though. (so they say).

kevinchristopherson said:
my problem more than once, ashamed to say. after updating drivers and cords. then forgot to pull my notifications down for that last little line. it's a learning process though. (so they say).
Click to expand...
Click to collapse
No worries dude even when you change default usb settings it still stays in charging mode

thatsupnow said:
You do realise that you've got to change the USB settings for it to do data transfer right???
Click to expand...
Click to collapse
Yup, I know that I need to change it to data transfer, however the phone isn't detected by either of my Windows laptops. The phone is only detected via ADB on my Chromebook. I can do an "adb reboot bootloader" and it'll accept the command, but "fastboot devices" or "lsusb" shows no devices.
kevinchristopherson said:
my problem more than once, ashamed to say. after updating drivers and cords. then forgot to pull my notifications down for that last little line. it's a learning process though. (so they say).
Click to expand...
Click to collapse
Yup, my first gen Pixel XL will notify me when I pull down the notifications, but the Pixel 3a doesn't.
I ended up setting up the phone and used it for a fewdays. It works fine, however I'm used to running AdAway, AFWall, EX Kernel Manager, Greenify, High Brightness Mode, NapTime, Titanium Backup and Viper4Android. There are workarounds to enable Greenify and NapTime via ADB, but it's a moot point without the other root dependent apps.

Updating this thread to close this out.
Bought a brand new Pixel 3a XL from the Google store. I was able to root without any issues on my Windows 10 laptop. I attempted the same exact process with the same USB port and USB cable for the Pixel 3a XL that I bought from Swappa, but it didn't work. This confirms my educated guess that it's a hardware issue on the phone.
The secondary market may soon be flooded with Pixel 3a XLs once the Pixel 4a is released. Before you get burned on a non-rootable phone, ask the seller how long they have owned the device and check the warranty on it. As of this post, you can check the IMEI Here: hxxps://store.google.com/repair (replace the hxxps with https).
Good luck!

You need to download the google usb driver and update the Pixel 3 driver in Device manager with the usb driver. Then the computer will recognize the phone as a fastboot device while it's in bootloader.

For me what solved this was I wasn't adding the "platform-tools" folder to my path.
I was using "fastboot.exe flashing unlock"
But once I added to path and did "fastboot flashing unlock" it worked like a charm

On Linux, did you try sudo fastboot flashing unlock? This is the only thing that works for me. Sudo before all fastboot commands.

In my case on Ubuntu 20.04, it was a USB 3.0 port problem. It was detect device with fastboot devices but other commands does not has a response. My laptop hasn't got a USB 2.0 port. Then I disabled internal USB 3.0 support in my BIOS and now fastboot is working normally. But all USB 3.0 support is stopped. It seems USB 2.0 hub is the better option. I will set back the BIOS setting later.

Yesterday i bought the G020B version, and the same happened to me while unlocking bootloader, fastboot keeps on <waiting for device> like if the phone was not even connected
I searched for a driver that could work and found this (For windows)
Basically, my system can't detect properly the phone because the driver was not 'updated'. (Even when i can use fastboot on other devices)
Hope it works for you or everyone here.

Question Phone not connecting via USB

My first Poco F3 is completely unlocked and running a custom rom, still able to connect to PC even now.
I have a second Poco F3 that I was able to originally connect to my PC to debloat, hadn't needed to connect it to a PC till now. Today was the day I could unlock it but when I connect it via USB cable, original or otherwise, no usb options appear on phone and nothing shows on PC. I can use the same cable on my first Poco F3 and everything works fine. I've tried multiple cables, reinstalling drivers, restarting phone and PC, trying a different PC, enabling debugging tools, etc.
Nothing shows in "My Computer"
Nothing shows in Device Manager
No usb options on phone (default is set to File Transfer)
Nothing shows in CMD with "adb devices"
Charging still works
Is there anything I can do to at the very least unlock the bootloader? Or is this not fixable?

long shot... check the usb C port for dirt/dust/fluff blocking connection...

Most probably u debloated an app responsable for media transfer. If u can, revert what u debloated.

Alin45 said:
Most probably u debloated an app responsable for media transfer. If u can, revert what u debloated.
Click to expand...
Click to collapse
Did a factory reset thinking that may have been the case, still no good.
Tried cleaning out the port and still no good either

I still think it's Windows. Please can you try putting Ubuntu (or another Linux distro) on a USB, booting from that, installing platform tools (ADB/fastboot etc) and then running ADB devices. Windows is very finiky sometimes.
Edit: when you plug in your phone to the PC do you get a notification saying charging? Or is there no notification? Also does it start charging the phone?

There is a delay before it begins charging and the charging animation plays but yes it does. But then there is no usb notification. Will try ubuntu and report back

Booting into Ubuntu, before installing platform tools the first phone that I knew worked showed up and showed up in adb devices when platform tools was used. The second still didn't show up, exactly the same as on windows

Try downloading the installed stock miui rom from the update menu in the miui update menu and re-install it on the phone

Unfortunately reinstalling latest package didn't help

Can't think of anything else to suggest. Sorry

If the usb connection continues to be nonexistent, is there any way to at least unlock the bootloader without using the Xiaomi Unlock tool on the PC?

Are you sure the USB cable you're using support transfert file?

Cjayy said:
If the usb connection continues to be nonexistent, is there any way to at least unlock the bootloader without using the Xiaomi Unlock tool on the PC?
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Click to collapse
Nope

Hmmmmm.....strange! I'm running out of ideas....try different USB ports on PC. Maybe it's a faulty USB-C port on phone after all.

do you have a type c usb-otg?
If yes then see if it is detected by the phone

X0PIRAT3 said:
Are you sure the USB cable you're using support transfert file?
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Click to collapse
Yes. Used 4 different cables, 1 of which is the cable that comes with the phone. None work on this phone but do on the first phone.
Alin45 said:
Hmmmmm.....strange! I'm running out of ideas....try different USB ports on PC. Maybe it's a faulty USB-C port on phone after all.
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Click to collapse
Tried different ports across 2 PCs. I'm starting to think it is a faulty port, though it worked fine a week ago.
arifqur said:
do you have a type c usb-otg?
If yes then see if it is detected by the phone
Click to expand...
Click to collapse
I honestly don't know if any of my cables are usb-otg, how would I check?

Try to use this version of Mi FLash Tool (only for drivers) : https://xiaomiflashtool.com/download/xiaomi-flash-tool-20210226
Extract and launch the executable then drivers install

Something like this. You can plug in any usb stick and see if it is detected. Another way to check whether the port on the phone is working for data as well

X0PIRAT3 said:
Try to use this version of Mi FLash Tool (only for drivers) : https://xiaomiflashtool.com/download/xiaomi-flash-tool-20210226
Extract and launch the executable then drivers install
Click to expand...
Click to collapse
Tried this and still no good.
arifqur said:
Something like this. You can plug in any usb stick and see if it is detected. Another way to check whether the port on the phone is working for data as well
Click to expand...
Click to collapse
I don't have anything like this but that reminded me of the usb-c to headphone adapter and that also doesn't work. Sound just plays out of the speakers.
Trying with Android Auto in the car, the car doesn't register a device connecting at all either.
Either the data transfer portion is somehow disabled on the device itself (which I would love to know how to enable it again if that's the case) or it's a damaged usb port. Just strange that it worked a week ago.
Something I forgot to mention, when I went to unlock the bootloader yesterday the phone did not show up anywhere except for in the ADBFastbootTools to debloat the software as a OnePlus device but then never showed up again.

Cjayy said:
Tried this and still no good.
I don't have anything like this but that reminded me of the usb-c to headphone adapter and that also doesn't work. Sound just plays out of the speakers.
Trying with Android Auto in the car, the car doesn't register a device connecting at all either.
Either the data transfer portion is somehow disabled on the device itself (which I would love to know how to enable it again if that's the case) or it's a damaged usb port. Just strange that it worked a week ago.
Something I forgot to mention, when I went to unlock the bootloader yesterday the phone did not show up anywhere except for in the ADBFastbootTools to debloat the software as a OnePlus device but then never showed up again.
Click to expand...
Click to collapse
I have the same problem, did you solve it ? I replaced the usb board of the phone, still not working.