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How To Guide The Quest for a Bootloader Unlock (partial guide, T-Mobile variant only)

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ttar ttar

Member
Apr 6, 2020
17
1
Does any one know why I got an error message when I tried "fastboot flash cust-unlock unlock_code.bin"?? Need help. Thanks so much in advance!
(I did receive the email from Oneplus for the download link for the approval device unlocking application)


C:\Users\alank\Downloads\Adb\Root\platform-tools_r29.0.6-windows\platform-tools>fastboot flash cust-unlock unlock_code.bin
Sending 'cust-unlock' (0 KB) OKAY [ 0.008s]
Writing 'cust-unlock' FAILED (remote: 'Error - Verify Failed ! (-1)')
fastboot: error: Command failed


UPDATE: Never mind. Guess the first download has some issues. Re-downloading and it works now. Thanks!
C:\Users\alank\Downloads\Adb\Root\platform-tools_r29.0.6-windows\platform-tools>fastboot flash cust-unlock unlock_code(1).bin
Sending 'cust-unlock' (0 KB) OKAY [ 0.009s]
Writing 'cust-unlock' (bootloader) Device is unlocked.
OKAY [ 0.007s]
Finished. Total time: 0.026s
 

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AiM2LeaRn

Member
Aug 11, 2021
27
6
once in fastboot make sure your window drivers are working, i had to install them manually AGAIN using the .inf and selected "Android Bootloader Interface"



Capture.PNG
 

edale1

Senior Member
Sep 5, 2016
68
36
once in fastboot make sure your window drivers are working, i had to install them manually AGAIN using the .inf and selected "Android Bootloader Interface"
Erm, yes, I did point out the phone had to be connected and in fastboot mode when you manually installed the fastboot drivers... What exactly was your issue?
You'll need to manually install the drivers through the device manager while the phone is in fastboot mode and connected to the PC (right-click -> Update Drivers -> Browse Computer -> Let Me Pick -> Have Disk).
The drivers should be located at:
C:\Users\[username]\AppData\Local\Android\Sdk\extras\google\usb_driver\android_winusb.inf
You'll want the 'Android Bootloader Interface' driver.
The PC is gonna use one of several drivers for the phone, depending on what mode the phone is in. It uses different drivers in fastboot mode than it does in recovery mode, which are different from the drivers when it's running normally.
 

AiM2LeaRn

Member
Aug 11, 2021
27
6
Erm, yes, I did point out the phone had to be connected and in fastboot mode when you manually installed the fastboot drivers... What exactly was your issue?

The fact i had to load the drivers manually AGAIN (as in more than once).. normally windows doesnt forget the drivers once loaded. Just figured it might help someone that had similar issue.
 

edale1

Senior Member
Sep 5, 2016
68
36
The fact i had to load the drivers manually AGAIN (as in more than once).. normally windows doesnt forget the drivers once loaded. Just figured it might help someone that had similar issue.
That probably meant the phone wasn't in fastboot mode when you manually installed the drivers the first time. That, or your PC has more pressing issues than an odd driver reversion.
 

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  • 5
    OK, this process has been hell, but I'm gonna try and consolidate everything I've worked out so far in one place. This all applies only to the T-Mobile variant (ie. it comes preloaded with all the T-Mobile bloatware) of the N200 on the T-Mobile network; and a Windows PC, where a PC is used (though I imagine the Mac/Linux commands are quite similar). This is more to gather the info in one place than to provide step-by-step instructions.

    SIM/NETWORK UNLOCK

    Before you can unlock the bootloader, the N200 needs to be SIM unlocked. The option to Enable OEM Unlock won't even show up in the developers options until then. A temporary SIM unlock won't work, it needs to be a permanent SIM unlock.

    If your N200 is the T-Mobile variant, you can get it SIM unlocked free here (be sure to read the first post thoroughly to be sure you qualify):
    @mobbdeep had my SIM unlocked within 24 hours of sending him the required info.
    You MUST have an active T-Mobile network (not Sprint or Metro) SIM card in the N200 for at least 3 full days before sending your SIM Unlock request in.

    ---
    *edit-
    An alternate is to use this debloat script:
    Which should unlock the OEM Unlock option in the developer options.
    This should work with non-T-Mobile variants of the N200 as well.
    Thanks to @PopCaps1996 for pointing this option out.
    ---

    Once your N200 is SIM Unlocked, the Enable OEM Unlock option will show up in the developers options.

    USB DRIVERS

    You may need to use the Google USB Driver from Android Studio to allow your PC to recognize your phone when it's in fastboot mode.
    Android Studio won't install the USB Drivers by default, you'll need to install them through the SDK Manager (Android Studio -> Projects -> More Actions -> SDK Manager -> SDK Tools -> Google USB Driver checkbox -> Apply)
    You'll need to manually install the drivers through the device manager while the phone is in fastboot mode and connected to the PC (right-click -> Update Drivers -> Browse Computer -> Let Me Pick -> Have Disk).
    The drivers should be located at:
    C:\Users\[username]\AppData\Local\Android\Sdk\extras\google\usb_driver\android_winusb.inf
    You'll want the 'Android Bootloader Interface' driver.

    UNLOCK CODE/TOKEN

    Once you can access your phone in fastboot mode, you can try:
    'fastboot oem unlock'
    But, you'll just get a message asking for an unlock token. Doesn't hurt to try, just in case, though.

    What you need to do now, is type:
    'fastboot oem get_unlock_code'
    This will display both the phone's serial number, plus a 64 digit unlock code. (you might not be able to select the code to copy it, but a ctrl-a / ctrl-c should work, then just paste it in notepad)

    Now, on your phone (still in fastboot mode) hit up/down on the volume buttons, until you see "Show Barcode", then tap the power button to select it.
    This will bring up a barcode, as well as listing you devices IMEI number. (there are other ways to get the IMEI, but this is quick, and you're already right there)
    Copy the IMEI down.

    Now go to:
    https://www.oneplus.com/unlock_token
    You'll need to create an account.

    In that form, you'll need to select the phone's model, and then enter the serial number, 64 digit unlock code (no spaces), the IMEI, and your email, as well as checking a box that you acknowledge that you void the warranty by bootloader unlocking the phone.

    If all goes well, It should take about a week from submission for them to send you the unlock token.

    ------

    I've just sent in my info an hour or two ago, and am now waiting for my unlock token.
    I'll update this with what you need to do with the token once I've gotten mine and figure it out myself, lol.

    ------

    Exactly 7 days (nearly to the minute) after sending the request in, I received the unlock code. So here's the update:

    APPLYING THE UNLOCK CODE

    You can use this URL to check the status of your Unlock Coed request:

    Once your Status is listed as "Finished", there will be a download button at the lower right corner.

    Download the "unlock_code.bin" file to your PC.

    Place 'unlock_code.bin' in:
    C:\Users\[user name]\AppData\Local\Android\Sdk\platform-tools\
    Or where ever you have your fastboot.exe file.
    If you don't know where it is, the command:
    Code:
    fastboot --version
    will give your it's location.

    Now in command line, navigate to the folder "fastboot.exe" and "unlock_code.bin" are located in. Get your phone connected via USB, and in fastboot mode, and use the following command:
    Code:
    fastboot flash cust-unlock unlock_code.bin
    (Thanks to @lentm for posting this command)
    After checking the output, to be sure it worked, use this command:
    Code:
    fastboot oem unlock
    Follow the on-screen instructions on your phone to finish the bootloader unlock.
    2
    you do NOT need to carrier unlocked for bootloader unlock use this...... debloat script oneplus through ADB an once finished OEM UNLOCK will be ungrayed. then you can request a unlock token from oneplus then wait 7 days then flash an unlock bootloader.
    im still carrier locked
    2
    Yep. Is there a way to add it back if it fails?
    I'd imagine a factory restore (via booting to the recovery partition) would re-install that no problem. Also wipe your data, but that's gonna happen when you get to the bootloader unlock anyways.

    As to specifically reinstalling just that? I honestly have no clue how to go about that, I'm not knowledgeable enough about Android's inner workings to even guess. I rarely ADB for anything but the rooting process when I get a new phone. There's a reason I said this guide was more for collecting the info in one place than providing a step-by-step guide, lol. I'm just trying to help everyone else, considering I spent days digging up all the info to try and get my bootloader unlocked.
    2
    Yes, but to my knowledge unlocking the bootloader is the only part of the entire process of installing a custom recovery and rooting that wipes the device. So it's best to get that out of the way ASAP, before the phone's loaded with stuff you don't want to lose.
    1
    you do NOT need to carrier unlocked for bootloader unlock use this...... debloat script oneplus through ADB an once finished OEM UNLOCK will be ungrayed. then you can request a unlock token from oneplus then wait 7 days then flash an unlock bootloader.
    im still carrier locked
    OK, that's neat.

    I can't personally test it, as I'm already SIM unlocked; but all comments in the thread seem to indicate it working.

    It'd be quite interesting if someone could narrow down exactly which of the removed apps enables the OEM Unlock option (as an uninformed guess: adb shell pm uninstall --user 0 com.qualcomm.qti.remoteSimlockAuth).

    I'd need to research what all those different apps do, but at a glance I see at least 2 or 3 on that list I'd want to keep. At any rate, I'd rather wait until after I get TWRP Recovery on my phone (once we get a release for the N200) before debloating it, just to be safe. I'm far more knowledgeable about computers than phones, which gives me just enough knowledge to seriously screw up my phone by doing the wrong thing, lol.