Develop Bugs

[Q] Unlock bootloader if Allowed=No for Z1C

Hi there,
I have a network unlocked Z1C which came from o2. The bootloader unlock allowed status is No but the phone is rooted. Is there anything I can do to this to unlock it? I feel like trying CM on it
Thanks!
I have searched for answers to this but no joy...
http://forum.xda-developers.com/search.php?searchid=280903320
http://forum.xda-developers.com/search.php?searchid=280903428

Comedy- said:
Hi there,
I have a network unlocked Z1C which came from o2. The bootloader unlock allowed status is No but the phone is rooted. Is there anything I can do to this to unlock it? I feel like trying CM on it
Thanks!
I have searched for answers to this but no joy...
http://forum.xda-developers.com/search.php?searchid=280903320
http://forum.xda-developers.com/search.php?searchid=280903428
Click to expand...
Click to collapse
brilliant... ive got a z1c comping in the post today and the only reason im upgrading to it from the xperia m is so i can flash a custom kernel and get tweaking

Comedy- said:
I have a network unlocked Z1C which came from o2. The bootloader unlock allowed status is No but the phone is rooted. Is there anything I can do to this to unlock it? I feel like trying CM on it
Click to expand...
Click to collapse
If your bootloader unlock allowed status is no then you will most likely never be able to unlock that phones bootloader. I think your best bet is to contact O2 and tell them you want a phone on which the bootloader is unlockable, perhaps they can give you a special key to unlock the functionality, but I wouldn't hold my breath.
Oh and don't try CM on it, it'll just bootloop and you'll have to use SUS or PC Companion to restore a working OS.
...actually there is one hope, but it requires dismantling the phone. There is a test-point behind the battery which might enable you to put the device into a mode where it'll accept a command allowing bootloader unlock. But again, high risk, not sure if it's actually possible, easier to just sell the phone and buy an unlockable one if you want to run CM. Maybe you could even return the device, how long have you had it?

my z1c just turned up and ive got an bootloader unlock allowed :victory::victory::victory:

I have locked bootloader on EE in UK and have found that many of the tweaks I wanted can be achieved with Xposed modules. Give it a try but backup before you start.

Need a opinion by a dev
Hello there,
I was thinking about a test.
My problem is "Unlock bootloader allowed : no".
What could happen if i restore an other TA partition with "Unlock bootloader allowed : yes". I erase the old by a new one which unlockable. All i need is a TA partition build with a z1c which unlockable and the unlock code.
What do you think ?
Soory for my bad english

If you replace your ta partition it will most likely hardbrick your device.

What is a ta partition, i don't understand.
A bootloader is like a bios on motherboard.
But it is locked by a code.
The bootloader is the same on each z1c no ?

Megani said:
What is a ta partition, i don't understand.
A bootloader is like a bios on motherboard.
But it is locked by a code.
The bootloader is the same on each z1c no ?
Click to expand...
Click to collapse
Flashing another phone's TA will hard brick yours, every TA is related to the phone which comes from

mindyabiznis said:
my z1c just turned up and ive got an bootloader unlock allowed :victory::victory::victory:
Click to expand...
Click to collapse
How you done this??? I tried hundred and half methods and still CAN'T unlock damn bootloader............

Should i check OEM unlocking option in the Developer settings ?

Ok so i have read many posts on XDA about bricked nexus 5x's and many others, sometimes the main probelm is the oem isnt unlocked. I myself have a Nexus 5x that is completely stock no custom recovery no root no nothing, i just update the phone, right now on Nougat 7.0 sep security update.
So my question is, should i check the OEM unlocking in the settings ? i will never install any recovery or root but i think by reading the posts, it seems like its a major problem if this is not checked, should i check it just to be safe ?

U_Midrar said:
Ok so i have read many posts on XDA about bricked nexus 5x's and many others, sometimes the main probelm is the oem isnt unlocked. I myself have a Nexus 5x that is completely stock no custom recovery no root no nothing, i just update the phone, right now on Nougat 7.0 sep security update.
So my question is, should i check the OEM unlocking in the settings ? i will never install any recovery or root but i think by reading the posts, it seems like its a major problem if this is not checked, should i check it just to be safe ?
Click to expand...
Click to collapse
If you have issues in your current state they will most likely be hardware related and unfixable via software. But even locked you can completely reinstall the OS via sideloading an OTA or using the TOT method.
Enabling OEM unlock disables Factory Reset Protection (FRP). FRP is a security feature that prevents a stolen device from being activated. There is allot of info about it online if you wish to learn more.
So you need to decide if you want FRP or the ability to flash the factory images.
Sent from my XT1650 using Tapatalk

PiousInquisitor said:
If you have issues in your current state they will most likely be hardware related and unfixable via software. But even locked you can completely reinstall the OS via sideloading an OTA or using the TOT method.
Enabling OEM unlock disables Factory Reset Protection (FRP). FRP is a security feature that prevents a stolen device from being activated. There is allot of info about it online if you wish to learn more.
So you need to decide if you want FRP or the ability to flash the factory images.
Click to expand...
Click to collapse
ok thx dude for the reply, nah i dont care about the FRP. so flashing factory images is easier right ? rather than sideloading or whatever this TOT method is...., and do most mobiles have a oem locked or unlocked ?

U_Midrar said:
ok thx dude for the reply, nah i dont care about the FRP. so flashing factory images is easier right ? rather than sideloading or whatever this TOT method is...., and do most mobiles have a oem locked or unlocked ?
Click to expand...
Click to collapse
Sure, flashing the factory images is probably slightly easier than the other methods. Note that in your case you would need to actually unlock the bootloader to flash the images. With those added steps it's probably faster to sideload.
The Allow OEM unlock toggle has been around since LP I think. An pretty sure it's in phones that shipped with LP. It didn't automagically mean that the phones bootloader can be unlocked though. It should stop disable FRP though.
Sent from my XT1650 using Tapatalk

Yes, most, I think all OEMs leave the possibility to unlock the bootloader.
By default the bootloader is locked on most OEMs (Sony, Samsung, HTC, Motorola, even Nexus devices).
For Nexus devices it's a simple one liner to unlock/lock the bootloader which will also trigger a data wipe but. On Nexus devices it doesn't void your warranty.
For most other OEMs phones you have to follow some steps and usually get some kind of code in order to unlock the bootloader the first time. This will void your warranty!
If you don't know whether or not you should unlock/lock the bootloader, the answer is: NO!
It seems you're not modifying your phones software (Custom Kernel, Custom Rom, Root etc) and you seem to have no intention doing so. So it's not needed and even less "secure" than with locked bootloader. If you do, you should know that you have to unlock the bootloader in order to change the phones software.
Why would you want to unlock the bootloader when the only reason to do so is to modify the software and you do not plan to do this?
On a stock nexus there is no need to unlock the bootloader, you can even reflash your phone with locked bootloader with the stock software image.

creambyemute said:
Yes, most, I think all OEMs leave the possibility to unlock the bootloader.
By default the bootloader is locked on most OEMs (Sony, Samsung, HTC, Motorola, even Nexus devices).
For Nexus devices it's a simple one liner to unlock/lock the bootloader which will also trigger a data wipe but. On Nexus devices it doesn't void your warranty.
For most other OEMs phones you have to follow some steps and usually get some kind of code in order to unlock the bootloader the first time. This will void your warranty!
If you don't know whether or not you should unlock/lock the bootloader, the answer is: NO!
It seems you're not modifying your phones software (Custom Kernel, Custom Rom, Root etc) and you seem to have no intention doing so. So it's not needed and even less "secure" than with locked bootloader. If you do, you should know that you have to unlock the bootloader in order to change the phones software.
Why would you want to unlock the bootloader when the only reason to do so is to modify the software and you do not plan to do this?
On a stock nexus there is no need to unlock the bootloader, you can even reflash your phone with locked bootloader with the stock software image.
Click to expand...
Click to collapse
yo dude thx for the reply, as i said in my first post, i saw some bricked nexus 5x (they didnt mod anything i think) that couldnt be repaired cause he had the option unchecked about OEM, that is why i was asking for like a safety precaution that if something goes wrong it would be okay cause oem could be unlocked then... what do u say now ? (and yea im not gonna ever mod anything in the phone, learned fom my last phone which i somehow bricked and a man fixed it for for 5$ )

U_Midrar said:
yo dude thx for the reply, as i said in my first post, i saw some bricked nexus 5x (they didnt mod anything i think) that couldnt be repaired cause he had the option unchecked about OEM, that is why i was asking for like a safety precaution that if something goes wrong it would be okay cause oem could be unlocked then... what do u say now ? (and yea im not gonna ever mod anything in the phone, learned fom my last phone which i somehow bricked and a man fixed it for for 5$ )
Click to expand...
Click to collapse
That catch is if if you checked OEM unloking and chose to not perform oem unlock command now.
When something did went wrong afterward, you are able to perform oem unlock but it will wipe your data.
There is no point for doing it.

HebeGuess said:
That catch is if if you checked OEM unloking and chose to not perform oem unlock command now.
When something did went wrong afterward, you are able to perform oem unlock but it will wipe your data.
There is no point for doing it.
Click to expand...
Click to collapse
so i shouldnt do it like just leave it be ?

F IT I DID IT
i just read this site and also got to know a bootloop can occur with OTA update so yea i have done it.
Site: http://android.wonderhowto.com/news...ting-before-modding-anything-android-0167840/

Relock Verizon Bootloader

I have my Verizon pixel xl unlocked with the sunshine mod from when I first got it. Can I relock the bootloader without the oem unlock setting being greyed out so I can unlock it in the future?

According to jcase, no.
http://theroot.ninja/depixel8.html said:
DO NOT RELOCK YOUR BOOTLOADER, unless you have restored it back to 100% stock and are sure you won't want it unlocked again.
Click to expand...
Click to collapse
Why do you want to relock it anyways?

fiveighteen said:
According to jcase, no.
Why do you want to relock it anyways?
Click to expand...
Click to collapse
While jcase was against it, after I have done my research, I attempted relocking my Verizon bootloader so I could send it out for RMA. I did it after I flashed the original factory image and made sure everything is back to OEM. So, I can tell you that it is possible. However, PLEASE don't take my words for it. Do your research and be 110% sure before you proceed. My heart was pounding so hard when I was trying to relock it because of the uncertainty... Anyway, do it at your own risk, I am just sharing you my experience, but please don't blame me if things go south

andrep182 said:
While jcase was against it, after I have done my research, I attempted relocking my Verizon bootloader so I could send it out for RMA. I did it after I flashed the original factory image and made sure everything is back to OEM. So, I can tell you that it is possible. However, PLEASE don't take my words for it. Do your research and be 110% sure before you proceed. My heart was pounding so hard when I was trying to relock it because of the uncertainty... Anyway, do it at your own risk, I am just sharing you my experience, but please don't blame me if things go south
Click to expand...
Click to collapse
Did you hit the slider too?
Were you able to unlock it again...if you tried?
Just curious and gathering info.....

TonikJDK said:
Did you hit the slider too?
Were you able to unlock it again...if you tried?
Just curious and gathering info.....
Click to expand...
Click to collapse
If by slider, you meant to ask if I locked it again, yes I did. I believe I relock it through fastboot.
There was really no point for me to unlock it again because I needed to send it for RMA so I never tried.

TonikJDK said:
Did you hit the slider too?
Were you able to unlock it again...if you tried?
Just curious and gathering info.....
Click to expand...
Click to collapse
If you unlock it and your already updated you won't be able to unlock again.

Haven't personally tried but I would be willing to bet a large sum of money if you relock it you will not be able to unlock it again I wouldn't even take the risk.

znel52 said:
Haven't personally tried but I would be willing to bet a large sum of money if you relock it you will not be able to unlock it again I wouldn't even take the risk.
Click to expand...
Click to collapse
I made the mistake of relocking and taking new updates. For sure, the unlock option was removed:
in first step of unlocking phone, the slider in Dev Options was forever greyed out. And it did not understand
fastboot unlock commands again. I would not recommend relocking Pixels for any reason other than return for
warranty repair.

michaelbsheldon said:
I made the mistake of relocking and taking new updates. For sure, the unlock option was removed:
in first step of unlocking phone, the slider in Dev Options was forever greyed out. And it did not understand
fastboot unlock commands again. I would not recommend relocking Pixels for any reason other than return for
warranty repair.
Click to expand...
Click to collapse
Locking on anything stock past 7.1 without root, would prohibit you from unlocking. If locking your BL + and no root capability = NO ability to unlock BL Thus what we have have So far, no known exploits...at least by me.

How to Lock Bootloader

Hello, I purchased a Pixel 3 XL off craigslist and it is working fine, but the bootloader is unlocked therefore I am receiving a warning when restarting the phone and Google Pay does not work. How can I re-lock the bootloader? Do I need to flash the latest standard google image? The build number is: "crosshatch-userdebug 9 PQ1A.181105.013 5027108 dev-keys". When in bootloader the bootloader version is: b1c1-0.1-5004167. Obviously a n00b here, please be gentle. Thank you for any help.

Do you have a computer? If so what OS do you use?
Sent from my Pixel 3 XL using Tapatalk

superchilpil said:
Do you have a computer? If so what OS do you use?
Sent from my Pixel 3 XL using Tapatalk
Click to expand...
Click to collapse
I do have a computer, a Windows 10 Pro

Are you planning on rooting? If so, you can use Magisk Hide (after using Magisk to root of course) to get Google Pay to work. I would be hesitant to re-lock the BL unless you are certain that it is completely stock otherwise. Re-locking a modified phone can brick the device. Better to just learn how to root, etc and keep it unlocked. You have come to the right place to learn.

sliding_billy said:
Are you planning on rooting? If so, you can use Magisk Hide (after using Magisk to root of course) to get Google Pay to work. I would be hesitant to re-lock the BL unless you are certain that it is completely stock otherwise. Re-locking a modified phone can brick the device. Better to just learn how to root, etc and keep it unlocked. You have come to the right place to learn.
Click to expand...
Click to collapse
No, I don't plan on rooting. But I am afraid of bricking the phone since I don't know what has been done to it. Is there a way to determine what was done to unlock the bootloader? Otherwise I will follow your recommendation of using Magisk Hide. I would prefer to keep the phone stock. Thanks.

eec007 said:
No, I don't plan on rooting. But I am afraid of bricking the phone since I don't know what has been done to it. Is there a way to determine what was done to unlock the bootloader? Otherwise I will follow your recommendation of using Magisk Hide. I would prefer to keep the phone stock. Thanks.
Click to expand...
Click to collapse
If you live in Denver I'll trade you my Verizon one for yours. It has a locked bootloader.

eec007 said:
No, I don't plan on rooting. But I am afraid of bricking the phone since I don't know what has been done to it. Is there a way to determine what was done to unlock the bootloader? Otherwise I will follow your recommendation of using Magisk Hide. I would prefer to keep the phone stock. Thanks.
Click to expand...
Click to collapse
The two obvious things you can check are that you have stock recovery and that the phone is not rooted. Manually power on to bootloader (hold volume down and press power then use the volume keys to select recovery and press power. you should get a no command android screen if in stock recovery. assuming you don't have a Magisk icon, you are probably not rooted but you can confirm by installing and running a root app like root checker. likely, the previous owner did nothing but unlock the BL given how recently it came out, but if someone where really creative they could have done work in the other partition. there are no exploites, so doing it normally (running fastboot flashing unlock from a prompt) is pretty much all that would have been done other than enabling developer options and OEM unlocking in settings.
Personally, I think you have a good chance to learn your device, root (you need to be rooted for Magisk hide) and keep the bootloader unlocked. Besides rooting, being able to install a full factory image instead of an OTA is so much better in my opinion. The amount of work it would take to be 100% confident that the only thing done was the BL unlock would take as much work as at least getting a working knowledge of rooting and reinstalling the OS.
P.S. Keeping a phone "stock and rooted" has advantages. That is how I run my 3 XL and how I ran my OG XL. No custom OS. Not even a kernel.

coolhandz said:
If you live in Denver I'll trade you my Verizon one for yours. It has a locked bootloader.
Click to expand...
Click to collapse
lol, what I don't get is that I thought the google edition could have the bootloader unlocked in the developer options. So why go to this hassle of unlocking the bootloader from fastboot? FYI, in the Developer options the OEM unlocking is greyed out and says "Bootloader is already unlocked".

sliding_billy said:
The two obvious things you can check are that you have stock recovery and that the phone is not rooted. Manually power on to bootloader (hold volume down and press power then use the volume keys to select recovery and press power. you should get a no command android screen if in stock recovery. assuming you don't have a Magisk icon, you are probably not rooted but you can confirm by installing and running a root app like root checker. likely, the previous owner did nothing but unlock the BL given how recently it came out, but if someone where really creative they could have done work in the other partition. there are no exploites, so doing it normally (running fastboot flashing unlock from a prompt) is pretty much all that would have been done other than enabling developer options and OEM unlocking in settings.
Personally, I think you have a good chance to learn your device, root (you need to be rooted for Magisk hide) and keep the bootloader unlocked. Besides rooting, being able to install a full factory image instead of an OTA is so much better in my opinion. The amount of work it would take to be 100% confident that the only thing done was the BL unlock would take as much work as at least getting a working knowledge of rooting and reinstalling the OS.
P.S. Keeping a phone "stock and rooted" has advantages. That is how I run my 3 XL and how I ran my OG XL. No custom OS. Not even a kernel.
Click to expand...
Click to collapse
Thank you! Root Checker says that "root access is not properly installed on this device". The recovery mode screen just has a warning about the bootloader is unlocked and a link to a google help page. I figure that I can always unlock the bootloader again if I need to later, but for now I just want everything to work (bank and pay app) and not worry about updating anything myself. I think I may try fastboot to lock the bootloader for now. Thanks for all the help.

Hope it all works out for you. I assume you did a factory reset on the device since you got it used. Re-locking will do another factory reset.

sliding_billy said:
Hope it all works out for you. I assume you did a factory reset on the device since you got it used. Re-locking will do another factory reset.
Click to expand...
Click to collapse
Yeah, so I locked using "fastboot flashing lock" but then it doesn't start, saying that there is no operating system or something like that. I freaked out and was able to unlock again using "fastboot flashing unlock". Now all is wiped. I guess I need to flash the oem rom first, then lock. I'll have to do this all later tonight. Just glad that I didn't brick it yet.

eec007 said:
Thank you! Root Checker says that "root access is not properly installed on this device". The recovery mode screen just has a warning about the bootloader is unlocked and a link to a google help page. I figure that I can always unlock the bootloader again if I need to later, but for now I just want everything to work (bank and pay app) and not worry about updating anything myself. I think I may try fastboot to lock the bootloader for now. Thanks for all the help.
Click to expand...
Click to collapse
I haven't rooted or bl unlocked in some time now so if I make a mistake someone please correct me. After buying it from a 3rd party I'd wipe the device entirely. Download the correct image and install the latest platform tools for Windows (here) https://developer.android.com/studio/releases/platform-tools and make sure you can connect with adb devices and fastboot devices commands. Then extract the latest full image from here https://developers.google.com/android/images to your platform-tools directory and run the flashall.bat command if you wish to wipe the entire device and get rid of anything the previous owner might have "inadvertently" installed. (this is what I would do but not necessarily what you should do if you want to keep the current apps and system intact) This will reset your device and then you can lock the bootloader with no worry and you'll have a stock system.
I agree that since you can unlock it at any time and you don't need it now then relock it. But there are those here that disagree with me and fight with Magisk and OTAs constantly. But they are not noobs and know what they're doing. If you want to learn there is a wealth of information here so it's your call. Just my 2 cents. But please check my steps before you do anything that might cause issues.
edit: darn, sorry I just saw above that you already tried to lock it. I hope what I said to do will get you out of the predicament.

bobby janow said:
I haven't rooted or bl unlocked in some time now so if I make a mistake someone please correct me. After buying it from a 3rd party I'd wipe the device entirely. Download the correct image and install the latest platform tools for Windows (here) https://developer.android.com/studio/releases/platform-tools and make sure you can connect with adb devices and fastboot devices commands. Then extract the latest full image from here https://developers.google.com/android/images to your platform-tools directory and run the flashall.bat command if you wish to wipe the entire device and get rid of anything the previous owner might have "inadvertently" installed. (this is what I would do but not necessarily what you should do if you want to keep the current apps and system intact) This will reset your device and then you can lock the bootloader with no worry and you'll have a stock system.
I agree that since you can unlock it at any time and you don't need it now then relock it. But there are those here that disagree with me and fight with Magisk and OTAs constantly. But they are not noobs and know what they're doing. If you want to learn there is a wealth of information here so it's your call. Just my 2 cents. But please check my steps before you do anything that might cause issues.
edit: darn, sorry I just saw above that you already tried to lock it. I hope what I said to do will get you out of the predicament.
Click to expand...
Click to collapse
Your steps are basically what I will try tonight. Currently the phone is working again, so there was no harm done yet (just the restore of all apps and such). But I'm going to flash the oem image tonight and start all over again.

eec007 said:
Your steps are basically what I will try tonight. Currently the phone is working again, so there was no harm done yet (just the restore of all apps and such). But I'm going to flash the oem image tonight and start all over again.
Click to expand...
Click to collapse
One thing I would do before I relocked the bl would be to do the full login procedure, email everything other than apps. Then make sure you're on the Nov update in about phone, I'm sure you will be, and then fastboot relock the bl with the proper command. It will wipe the device again but it's a small price to pay for about 10 minutes of work. Then once it reboots and there is no more error message you'll be fully stock. Enable dev options again and make sure the oem switch is active allowing bl unlock. Then you're done. I've gotten to the point on my 5X where I even flip the oem switch so it can't be bl unlocked until I go in and flip it back. Dangerous if you're flashing stuff but not so much if you're just taking OTAs. That's of course your call entirely. Good luck.

eec007 said:
lol, what I don't get is that I thought the google edition could have the bootloader unlocked in the developer options. So why go to this hassle of unlocking the bootloader from fastboot? FYI, in the Developer options the OEM unlocking is greyed out and says "Bootloader is already unlocked".
Click to expand...
Click to collapse
That will stay grayed out until you relock the bootloader. That slider "allows" unlocking. Then you boot into fastboot and unlock it.
So you would reverse the process, hit fastboot and relock the bootloader. Then you can toggle the slider back to not allow unlocking.
Relocking the bootloader will wipe your phone.
You should not do this until you first flash the full factory image to make sure the phone is 100 percent stock. And if it were my phone I would wait for the next OTA update after flashing it back to stock to make sure it goes ok. Then lock it.
And then I would wait awhile before hitting the slider.
You are playing with fire here, if you mess it up and lock it and hit the slider you will not be able to fix it. And no offense, but since you have not done this all before on this phone chances are good you will mess it up.
So, flash to stock and leave it unlocked.
Then wait for the next OTA.
Then lock it.
Then wait a bit more before you hit the slider.
And remember, since you are not the original buyer you will not be able to warranty it.

eec007 said:
Hello, I purchased a Pixel 3 XL off craigslist and it is working fine, but the bootloader is unlocked therefore I am receiving a warning when restarting the phone and Google Pay does not work. How can I re-lock the bootloader? Do I need to flash the latest standard google image? The build number is: "crosshatch-userdebug 9 PQ1A.181105.013 5027108 dev-keys". When in bootloader the bootloader version is: b1c1-0.1-5004167. Obviously a n00b here, please be gentle. Thank you for any help.
Click to expand...
Click to collapse
They're right to mention that relocking a modified device can result in a brick.
Your best bet is to go to https://developers.google.com/android/images#taimen
Follow the directions to the "T", then relock it if you are really really sure that the unlock screen bothers you.
Would suggest to do this anyway, no matter future unlock status.

TonikJDK said:
That will stay grayed out until you relock the bootloader. That slider "allows" unlocking. Then you boot into fastboot and unlock it.
So you would reverse the process, hit fastboot and relock the bootloader. Then you can toggle the slider back to not allow unlocking.
Relocking the bootloader will wipe your phone.
You should not do this until you first flash the full factory image to make sure the phone is 100 percent stock. And if it were my phone I would wait for the next OTA update after flashing it back to stock to make sure it goes ok. Then lock it.
And then I would wait awhile before hitting the slider.
You are playing with fire here, if you mess it up and lock it and hit the slider you will not be able to fix it. And no offense, but since you have not done this all before on this phone chances are good you will mess it up.
So, flash to stock and leave it unlocked.
Then wait for the next OTA.
Then lock it.
Then wait a bit more before you hit the slider.
And remember, since you are not the original buyer you will not be able to warranty it.
Click to expand...
Click to collapse
I agree with most of your post other than waiting for the next OTA before you lock the bootloader. Why would he need to do that? If he's stock, and he'll see that immediately, then relock it. He doesn't want root or Magisk but only wants banking and Pay. With the slider allowing bl unlock he's in no danger whatsoever. Lock and relock whenever he wants. OTA will not disallow the slider once it's set.

TonikJDK said:
That will stay grayed out until you relock the bootloader. That slider "allows" unlocking. Then you boot into fastboot and unlock it.
So you would reverse the process, hit fastboot and relock the bootloader. Then you can toggle the slider back to not allow unlocking.
Relocking the bootloader will wipe your phone.
You should not do this until you first flash the full factory image to make sure the phone is 100 percent stock. And if it were my phone I would wait for the next OTA update after flashing it back to stock to make sure it goes ok. Then lock it.
And then I would wait awhile before hitting the slider.
You are playing with fire here, if you mess it up and lock it and hit the slider you will not be able to fix it. And no offense, but since you have not done this all before on this phone chances are good you will mess it up.
So, flash to stock and leave it unlocked.
Then wait for the next OTA.
Then lock it.
Then wait a bit more before you hit the slider.
And remember, since you are not the original buyer you will not be able to warranty it.
Click to expand...
Click to collapse
Thank you for explaining this. I had thought that the Developer Option slider was to unlock the bootloader, but your explanation clarifies it, the slider is to allow the bootloader to be unlocked...

Ok, so I tried to flash the factory image using adb flash-all and it keeps getting the error:
Sending sparse 'vendor_a' 2/2 (193888 KB) FAILED (Error reading sparse file)
Now the phone is not working at all and says that "device is corrupt" and will not boot past the white google screen. I can try again using adb, but it is the same error each time. I tried to download the image again and same sparse error. I can also fastboot in TWRP, but not sure what to do in there. What am I doing wrong? I guess I should've rooted and used Magisk like others have said.

turns out changing to a different cable resolved my sparse error and I was then successfully able to apply the factory image and lock the device. Thanks everyone for the help.

Any way to remove unlocked bootloader message?

I do not want to relock my bootloader, but I want to get rid of the nag screen at boot that bootloader is unlocked. Just in case my phone will get into wrong hands that is like an open invitation to hack it.
I remember I used to replace this logo with a neutral black screen on one of my previous devices. Isn't that possible anymore nowdays?
Yes, I understand that is not a perfect security. A perfect security is if my phone will be kept in a safe in a swiss bank with keys lost. Just trying not to give obvious hints.

EDIT:
LOL sorry I don't know how but I missed first 8 words in Your post. Don't read my reply it won't help.
Hi.
I was converting from Tmobile to global. To get rid from that messege I simply locked the bootloader. I'm not sure if u want to lock it or you are looking for some kind of way around it. If you would like to do it remember its very important to do it after taking OTA otherwise you can have some problems with your phone. That was mine steps:
Unlock bootloader.
Flash global.
Do OTA.
Lock bootloader with "fastboot oem lock".
Hope it helps. Regards.

thardy00 said:
EDIT:
LOL sorry I don't know how but I missed first 8 words in Your post. Don't read my reply it won't help.
Hi.
I was converting from Tmobile to global. To get rid from that messege I simply locked the bootloader. I'm not sure if u want to lock it or you are looking for some kind of way around it. If you would like to do it remember its very important to do it after taking OTA otherwise you can have some problems with your phone. That was mine steps:
Unlock bootloader.
Flash global.
Do OTA.
Lock bootloader with "fastboot oem lock".
Hope it helps. Regards.
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LOL, yeah! This happens