Develop Bugs

Cannot boot into bootloader/fastboot

Hello guys I have H815 and I can't proceed with unlocking bootloader cause my phone cannot boot into bootloader/fastboot mode. I'm not newbie, but with this phone everything goes ****ing different than in instruction.
I the instruction there is adb reboot bootloader. Of course my phone is seen in adb mode but after this command it just reboot to system. I tried also key combinations with no luck...
What to do?
My system is android 6

remialfa said:
Hello guys I have H815 and I can't proceed with unlocking bootloader cause my phone cannot boot into bootloader/fastboot mode. I'm not newbie, but with this phone everything goes ****ing different than in instruction.
I the instruction there is adb reboot bootloader. Of course my phone is seen in adb mode but after this command it just reboot to system. I tried also key combinations with no luck...
What to do?
My system is android 6
Click to expand...
Click to collapse
Hi,
I'm the same...
looking for solution I found this on Youtube:
Pratically, you have to press vol up while connect USB on PC....
I haven't the G4 with my today and so I cannot test if this is a valid mode...
If you do this, let me know if you can enter in fastboot mode

auceto63 said:
Hi,
I'm the same...
looking for solution I found this on Youtube:
Pratically, you have to press vol up while connect USB on PC....
I haven't the G4 with my today and so I cannot test if this is a valid mode...
If you do this, let me know if you can enter in fastboot mode
Click to expand...
Click to collapse
I did that and yeah it entered this mode but it's not valid bootloader/fastboot mode. It's some service mode to update firmware. Anyway it's not visible in pc as a normal fastboot and I cannot proceed further with unlocking bootloader...
Edit: it's download mode... So as I said it's not fastboot mode.
Anyone can help?

Seriously nobody? I thought this phone has good community and support...

I'm facing the exact same problem with my H810 on 6.0. Sick of not being able to root atleast.
Seriously hasn't anyone on earth found a way to boot this **** in fastboot? I mean there are a number of tutorials but everything goes different as F*** with this thing. Hope someone will update with good news. :fingers-crossed::fingers-crossed:

charith262 said:
I'm facing the exact same problem with my H810 on 6.0. Sick of not being able to root atleast.
Seriously hasn't anyone on earth found a way to boot this **** in fastboot? I mean there are a number of tutorials but everything goes different as F*** with this thing. Hope someone will update with good news. :fingers-crossed::fingers-crossed:
Click to expand...
Click to collapse
You can check out UsU. That is an unofficial bootloader unlock

ThePiGuy said:
You can check out UsU. That is an unofficial bootloader unlock
Click to expand...
Click to collapse
Thanks yeah I checked but that's for ARB<=2 devices. I forgot to mention earlier this godforsaken thing is ARB3.

I have an H811 (T-Mo) running firmware H81120p, ARB3. Doesn't seem to be much that can be done with it as far as rooting. It also has no stock recovery, only boots to system.

you did follow this official guide right? it unlocked mine after a few angry moments
http://developer.lge.com/resource/mobile/RetrieveBootloader.dev
use minimal ADB https://forum.xda-developers.com/showthread.php?t=2317790
Only way to boot twrp later is to use fastboot with ADB, recovery with buttons doesn't work.
if the device wont boot a rom use adb to get back in recovery.
if you use bank apps, install magisk before installing rom, do not get SU

samadee3 said:
you did follow this official guide right? it unlocked mine after a few angry moments
http://developer.lge.com/resource/mobile/RetrieveBootloader.dev
use minimal ADB https://forum.xda-developers.com/showthread.php?t=2317790
Only way to boot twrp later is to use fastboot with ADB, recovery with buttons doesn't work.
if the device wont boot a rom use adb to get back in recovery.
Click to expand...
Click to collapse
Only problem is that the info linked to above applies to ONE G4 variant only - the H815 international model. The rest of us are SOL. The bootloader on US carrier G4 - AT&T, T-Mo, VzW, etc (most later firmware revisions for G3 as well) models has been nailed down. The only exception is a G4 with ARB <= 2 can be hacked with UsU in order to root it and install a custom recovery.

SofaSpud said:
Only problem is that the info linked to above applies to ONE G4 variant only - the H815 international model. The rest of us are SOL. The bootloader on US carrier G4 - AT&T, T-Mo, VzW, etc (most later firmware revisions for G3 as well) models has been nailed down. The only exception is a G4 with ARB <= 2 can be hacked with UsU in order to root it and install a custom recovery.
Click to expand...
Click to collapse
Tmo is very easy
Go to dev options and enable adb
Then run "adb reboot bootloader"
Once there, run "fastboot oem unlock" and voila, you have an officially unlocked bootloader with no restrictions related to UsU
Please be aware the above will factory reset your device

ThePiGuy said:
Tmo is very easy
Go to dev options and enable adb
Then run "adb reboot bootloader"
Once there, run "fastboot oem unlock" and voila, you have an officially unlocked bootloader with no restrictions related to UsU
Please be aware the above will factory reset your device
Click to expand...
Click to collapse
Do you know anyone who has done it with H81120o or later? I've seen posts for two yrs about doing it that way, but I don't remember reading about it being done on 20o or later.
Sent from my SAMSUNG-SM-G935A using Tapatalk

SofaSpud said:
Do you know anyone who has done it with H81120o or later? I've seen posts for two yrs about doing it that way, but I don't remember reading about it being done on 20o or later.
Click to expand...
Click to collapse
Why v20o
Remember, this has nothing to do with UsU and therefore ARB etc doesn't matter
Edit: ps there are loads of H811 users in my Lineage thread and the other ROMs too

ThePiGuy said:
Why v20o
Remember, this has nothing to do with UsU and therefore ARB etc doesn't matter
Edit: ps there are loads of H811 users in my Lineage thread and the other ROMs too
Click to expand...
Click to collapse
Got it. Guess that it makes sense. ARB prevents rolling back to earlier release than 20o, I'm ok. Will try the BL unlock today then.
Sent from my SAMSUNG-SM-G935A using Tapatalk

I actually managed to get my LG V20 F800L into same situation after messing up my rooting process.
First i was stuck at logo and factory reset did nothing. Bootloader was working then.
Then i downloaded new firmware through "Download Mode", and after that i lost access to bootloader.
I know the phone model is different, but process seems to be very similar for all LG devices.
Trying to troubleshoot that atm, if i'll have results i'll post them here.
P.S. I know original poster long left (probably after throwing phone into a grinder), but maybe for someone with same problem as us in the future the info will be useful.

Florimer said:
I actually managed to get my LG V20 F800L into same situation after messing up my rooting process.
First i was stuck at logo and factory reset did nothing. Bootloader was working then.
Then i downloaded new firmware through "Download Mode", and after that i lost access to bootloader.
I know the phone model is different, but process seems to be very similar for all LG devices.
Trying to troubleshoot that atm, if i'll have results i'll post them here.
P.S. I know original poster long left (probably after throwing phone into a grinder), but maybe for someone with same problem as us in the future the info will be useful.
Click to expand...
Click to collapse
Ok, now i have to reply to my own post, since i believe i understand now something important:
LG phones usually dont have bootloader open to access. Until you use some exploits to do so.
I did not know that at the time of writing that reply.

Florimer said:
Ok, now i have to reply to my own post, since i believe i understand now something important:
LG phones usually dont have bootloader open to access. Until you use some exploits to do so.
I did not know that at the time of writing that reply.
Click to expand...
Click to collapse
Do you have more details about this? I seem to be in a similar situation than you and I'm struggling to make it work.

LG V30+ download missing, root gone, and bootloader locked

I would like to thank everyone for there support for this most awesome but difficult phone. I have an unlocked US LG V30+ phone which an error in cross flashing accidently caused my phone to loose everything I needed to use LGUP. Does anyone know of an exe rom to flash on this phone to regain download option or a full restore to start fresh to do the rooting the right way? I know some mobile devices have exe for full restore but haven't found one for this phone yet.
Thanks again and I hope for a possible positive answer.

mcarden2006 said:
I would like to thank everyone for there support for this most awesome but difficult phone. I have an unlocked US LG V30+ phone which an error in cross flashing accidently caused my phone to loose everything I needed to use LGUP. Does anyone know of an exe rom to flash on this phone to regain download option or a full restore to start fresh to do the rooting the right way? I know some mobile devices have exe for full restore but haven't found one for this phone yet.
Thanks again and I hope for a possible positive answer.
Click to expand...
Click to collapse
Your bootloader is NOT relocked unless you flashed fastboot command to re-lock it.
Your bootloader is still unlocked.

ChazzMatt said:
Your bootloader is NOT relocked unless you flashed fastboot command to re-lock it.
Your bootloader is still unlocked.
Click to expand...
Click to collapse
It's locked.

mcarden2006 said:
It's locked.
Click to expand...
Click to collapse
Then start over to unlock bootloader https://forum.xda-developers.com/showpost.php?p=76584629&postcount=193

The bootloader for the G8s can be unlocked!!

I entered my device info (European G8s) on the LG bootloader unlock page and they actually sent me a key
I flashed it and the bootloader is now unlocked.
Are there any custom recoveries for the G8 so I can root it?
Confirmation SS: https://i.gyazo.com/c462abdb50c9b9b4f985a72d4c17c3cc.png
Flashing: https://i.gyazo.com/a35d0baebc4e1fcfa6ab2d2697e0709c.png
Confirming flash: https://i.gyazo.com/cbc958227bbdf75496f8b78ca0601086.png

Yup, I unlocked mine as well. Hope someone develops custom recovery and rom.

hej2010 said:
I entered my device info (European G8s) on the LG bootloader unlock page and they actually sent me a key
I flashed it and the bootloader is now unlocked.
Are there any custom recoveries for the G8 so I can root it?
Confirmation SS: https://i.gyazo.com/c462abdb50c9b9b4f985a72d4c17c3cc.png
Flashing: https://i.gyazo.com/a35d0baebc4e1fcfa6ab2d2697e0709c.png
Confirming flash: https://i.gyazo.com/cbc958227bbdf75496f8b78ca0601086.png
Click to expand...
Click to collapse
You can root without twrp in fastboot. No custom ROMs because most people can't unlock bl...

Just tried with my LMG820QM. Does not work. I was hoping it would because the G8s isn't on the list either.

Thank you.
If anyone has the stock boot.img of the EAUW (I think? the one with W) variant, please upload it
I can't manage to unpack the KDZ and get to the img but I would really love to get root already

Frau Son said:
Thank you.
If anyone has the stock boot.img of the EAUW (I think? the one with W) variant, please upload it
I can't manage to unpack the KDZ and get to the img but I would really love to get root already
Click to expand...
Click to collapse
How did you get the KDZ? Can you send/upload it?
Edit: I downloaded a KDZ and got it extracted using https://github.com/steadfasterX/kdztools.
Will try to patch the boot image with magisk

hej2010
Thank you best news this year wait since last year,i no longer believed in it :laugh: . I love the LG 8s today more :victory:
I have the "DEC" LMG810EAW is working ,i hope beginning developer make custom roms ,kernel,TWRP and camera mods :highfive: :victory:

Root is working!!!
I patched the boot image with magisk and it works
Edit: wrote a small guide here: https://forum.xda-developers.com/lg-g8/how-to/rooting-g8s-guide-t4044193

hej2010 said:
Root is working!!!
I patched the boot image with magisk and it works
Edit: wrote a small guide here: https://forum.xda-developers.com/lg-g8/how-to/rooting-g8s-guide-t4044193
Click to expand...
Click to collapse
You are an ANGEL!
Thank you so, so much, you made my evening!
:fingers-crossed:

I was able to unlock my G8s LM-G810EAW aswell
Let's hope there will be a custom recovery soon!

Anybody with unlocked bootloader already tried to flash a gsi?
According to the G8, v50 telegram group gsi are fully working on the g8 without any special adaptions.

Anyone know how to unlock the LM-G850QM version?
Can't seem to find a way yet.

How do you lock the bootloader?
I bought an unlocked LG G8 ThinQ US Cellular version here in HK. Works perfectly fine but I receive the bootloader is unlocked message when loading up. As a result (or at least I think it's linked), when I try and install any banking app for Citibank on my phone, it insists my phone is rooted and I cannot use it. I have checked with as many different apps as possible and they all insist that the phone is not rooted. I don't need/want the phone to be rooted and I want the banking app to work on my phone, so I am trying to lock the bootloader. Apparently, this is doable using ADB and loading in fastboot, unfortunately, I cannot load the phone into fastboot mode. Any ideas on how I can lock the bootloader as it's not clear how it was unlocked in the first place? The version I have is LMT600US.
Also, if anyone knows whether locking the bootloader will somehow render my phone unusable - that would also be helpful as I clearly don't want to do that? :good:

djoseph852 said:
I bought an unlocked LG G8 ThinQ US Cellular version here in HK. Works perfectly fine but I receive the bootloader is unlocked message when loading up. As a result (or at least I think it's linked), when I try and install any banking app for Citibank on my phone, it insists my phone is rooted and I cannot use it. I have checked with as many different apps as possible and they all insist that the phone is not rooted. I don't need/want the phone to be rooted and I want the banking app to work on my phone, so I am trying to lock the bootloader. Apparently, this is doable using ADB and loading in fastboot, unfortunately, I cannot load the phone into fastboot mode. Any ideas on how I can lock the bootloader as it's not clear how it was unlocked in the first place? The version I have is LMT600US.
Also, if anyone knows whether locking the bootloader will somehow render my phone unusable - that would also be helpful as I clearly don't want to do that? :good:
Click to expand...
Click to collapse
Well, you can first try to install magisk manager and try to enable magisk hide (the default settings for play services and for your banking apps). If it says you don't have magisk, make sure you try and backup your boot img first and then click direct install. You can also hide magisk manager in settings. If you still don't pass safety net, clear data for Google apps and look up the pxl4xlprops module

I have an LM-G810EAW with Android 10 (V20a-EEA-XX) and tried to unlock the bootloader. Got unlock.bin from LG and tried to flash it, but got the message:
Code:
> fastboot flash unlock ./unlock.bin
Sending 'unlock' (1 KB) OKAY [ 0.009s]
Writing 'unlock' FAILED (remote: 'Flashing Unlock is not allowed')
fastboot: error: Command failed
Have I missed something?
EDIT:
YES, I missed to enable OEM Unlock!

hej2010 said:
I entered my device info (European G8s) on the LG bootloader unlock page and they actually sent me a key
I flashed it and the bootloader is now unlocked.
Are there any custom recoveries for the G8 so I can root it?
Confirmation SS: https://i.gyazo.com/c462abdb50c9b9b4f985a72d4c17c3cc.png
Flashing: https://i.gyazo.com/a35d0baebc4e1fcfa6ab2d2697e0709c.png
Confirming flash: https://i.gyazo.com/cbc958227bbdf75496f8b78ca0601086.png
Click to expand...
Click to collapse
I need Lg up & Dll for my lg g8 s LM-G820N

[G8s] is unlock for other variants possible?

Is there any way to unlock the non european variants of G8s? G810EA, not EAW.
Tried on LG dev page it refuses saying not supported but my fastboot shows option to write a BL unlock key and says it can be unlocked.
Any possibility of getting unlocked BL another way? Im open to unofficial methods.
Many thanks

corpsegrinder62 said:
Is there any way to unlock the non european variants of G8s? G810EA, not EAW.
Tried on LG dev page it refuses saying not supported but my fastboot shows option to write a BL unlock key and says it can be unlocked.
Any possibility of getting unlocked BL another way? Im open to unofficial methods.
Many thanks
Click to expand...
Click to collapse
Well I think the bl unlock method for a while for v40 and g7 was crossflashing to a firmware with fastboot and fastboot booting (not flashing) a magisk patched boot IMG, then using the root to dd flash the engineering abl which allows unlocking. I don't know if that would work for g8s without a brick or if your fastboot even allows fastboot booting

antintin said:
Well I think the bl unlock method for a while for v40 and g7 was crossflashing to a firmware with fastboot and fastboot booting (not flashing) a magisk patched boot IMG, then using the root to dd flash the engineering abl which allows unlocking. I don't know if that would work for g8s without a brick or if your fastboot even allows fastboot booting
Click to expand...
Click to collapse
Thanks alot for the response, that's very hopeful! any place you could point me to the process of flashing the engineering abl? not even sure were to start looking for it on the G8s. P.S im not a noob just a noob to LG
I think my fastboot would allow booting as it does respond to basic commands i've tried so far, only issue is the boot.img's out there are all for the EAW version, anyway to decompile a boot img from a kdz?
Thanks in advance!

corpsegrinder62 said:
Thanks alot for the response, that's very hopeful! any place you could point me to the process of flashing the engineering abl? not even sure were to start looking for it on the G8s. P.S im not a noob just a noob to LG
I think my fastboot would allow booting as it does respond to basic commands i've tried so far, only issue is the boot.img's out there are all for the EAW version, anyway to decompile a boot img from a kdz?
Thanks in advance!
Click to expand...
Click to collapse
Yeah, download the kdz for the exact software version you're on, look up kdztools steadfasterx, go on the GitHub, extract the boot IMG, and patch it in the magisk app. Then try fastboot booting it; flashing it without bl unlock would make it not let you boot, but since fastboot booting worked on g7 and v40, I'd assume it would be ok. You might want to join the telegram group and find someone who knows for certain though

antintin said:
Yeah, download the kdz for the exact software version you're on, look up kdztools steadfasterx, go on the GitHub, extract the boot IMG, and patch it in the magisk app. Then try fastboot booting it; flashing it without bl unlock would make it not let you boot, but since fastboot booting worked on g7 and v40, I'd assume it would be ok. You might want to join the telegram group and find someone who knows for certain though
Click to expand...
Click to collapse
Thanks, im going to try this really appreciate your help here. and the abl any idea how i go about flashing that to unlock? Patching the main boot img from magisk while still locked even if the boot img boots with fastboot obviously still won't work to write boot partition with locked BL would it?
thanks i am in that group and asked several times but got ignored, thats why i thought i would ask here, there are 8 countries on this variant so i figured it would help all if it could be figured out since LG Dev only supports the euro model and this variant can actually be unlocked

corpsegrinder62 said:
Thanks, im going to try this really appreciate your help here. and the abl any idea how i go about flashing that to unlock? Patching the main boot img from magisk while still locked even if the boot img boots with fastboot obviously still won't work to write boot partition with locked BL would it?
thanks i am in that group and asked several times but got ignored, thats why i thought i would ask here, there are 8 countries on this variant so i figured it would help all if it could be figured out since LG Dev only supports the euro model and this variant can actually be unlocked
Click to expand...
Click to collapse
Worry about that later, first figure out if you can fastboot boot a boot IMG. Fastboot flashing it will 100% brick you

antintin said:
Worry about that later, first figure out if you can fastboot boot a boot IMG. Fastboot flashing it will 100% brick you
Click to expand...
Click to collapse
Thanks again, so here is the result.
I am struggling with both kdz tools and kdz firmware extractor, im able to get the DZ and dll files out, but on kdz tools using undz i end up with a bunch of .chunk files, and firmware extractor gives a zlib deflate error and gives a 0 byte file,
Taking this one side, i tried to rename the .chunk to a .img file, fastboot proceeded to download and attempt to boot, but stuck at logo, im guessing because the extraction of the boot img wasn't successful. but fastboot command worked and downloading to the phone worked, and it did attempt to boot, i have no idea now though how to get this kdz extracted. so needless to say without a working boot img i can't confirm 100% all i can confirm is fastboot boot command works.
any ideas?
[EDIT] i changed the unkdz to -c command, it extracted a boot img, i did as you said, patched boot img with magisk, and tried to fastboot boot it, sure enough! booted with dev warning error popups, but went into magisk, root access granted! so the patched boot img works by fastboot booting.
How would i go about the rest though with abl? as far as im aware we still waiting for firehose for G8/s?

corpsegrinder62 said:
Thanks again, so here is the result.
I am struggling with both kdz tools and kdz firmware extractor, im able to get the DZ and dll files out, but on kdz tools using undz i end up with a bunch of .chunk files, and firmware extractor gives a zlib deflate error and gives a 0 byte file,
Taking this one side, i tried to rename the .chunk to a .img file, fastboot proceeded to download and attempt to boot, but stuck at logo, im guessing because the extraction of the boot img wasn't successful. but fastboot command worked and downloading to the phone worked, and it did attempt to boot, i have no idea now though how to get this kdz extracted. so needless to say without a working boot img i can't confirm 100% all i can confirm is fastboot boot command works.
any ideas?
[EDIT] i changed the unkdz to -c command, it extracted a boot img, i did as you said, patched boot img with magisk, and tried to fastboot boot it, sure enough! booted with dev warning error popups, but went into magisk, root access granted! so the patched boot img works by fastboot booting.
How would i go about the rest though with abl? as far as im aware we still waiting for firehose for G8/s?
Click to expand...
Click to collapse
Nice, now you basically have to do the same thing as the other bl unlock guides. You flash the engineering abl to slot b (while on slot a) which needs to have working pie on it. Then you switch to it, go to fastboot, and do fastboot oem unlock.

antintin said:
Nice, now you basically have to do the same thing as the other bl unlock guides. You flash the engineering abl to slot b (while on slot a) which needs to have working pie on it. Then you switch to it, go to fastboot, and do fastboot oem unlock.
Click to expand...
Click to collapse
Thats great! When you say flash though. You mean dd flash with terminal with su to flash boot_b using said root access right? Then using fastboot to switch to boot_b and use that to unlock, correct?
But no abl yet for G8s as far as im aware, so i take it we need to wait on firehose for it or would cross flashing abl from another device work? Also android 10 update is around the corner, im still on pie 10i for now.
Thanks alot for your patience to help

Question Can't re-lock t-mobile bootloader

It is still completely stock but I am getting:
C:\Users\nickt\Desktop\platform-tools>fastboot oem lock
FAILED (remote: 'Please flash unlock token first.')
fastboot: error: Command failed

Just flash stock msm

FizzyAps said:
Just flash stock msm
Click to expand...
Click to collapse
I'm not sure how to do that or where to find the factory image

Actually I remember I have the MSM tool and it doesn't recognize my op9p

Nickdroid86 said:
Actually I remember I have the MSM tool and it doesn't recognize my op9p
Click to expand...
Click to collapse
I can help dm me

I got it! Thank you though. I had to find the unlock bin file and flash it again first for some reason

Please change the thread title to (Solved). . . So that people will know it's resolved and others who have the same issue can find your resolution. Remember, with tmo you have to put the code when you unlock or lock the bootloader everytime. Happy modding!