Can't unlock phone

[ottpeter]

I used to have an issue that is detailed here:

Computer can't see the phone after failed install

I tried to install Ubuntu touch through UBports installer, it downloaded some files, then it downloaded some more files, it restarted, there was an error, after that, the computer can’t see the phone again, and I can only go to fastboot. For some time, I was able to go to Recovery mode as well, but now I can only reach fastboot, where I can see my model, and that the bootloader is unlocked. I tried it on Windows as well, originally, I was trying to install the phone through a Debian VM. It’s n…

Basically, I bricked my phone and had to send it to France for repair. Now the phone works again with stock ROM (which I don’t want, I want LineageOS or Ubuntu Touch), BUT, I can’t unlock the bootloader anymore. The process goes through with the unlock code, everything seems to be fine, but it will write Locked, when starting the bootloader.

I don’t know why is this, my guess is that it was re-installed with some strange version of the stock ROM, that will not allow the bootloader to e unlocked. How to fix this? Do I need to send my phone to France for repair again?

[yvmuell]

@ottpeter

The process goes through with the unlock code, everything seems to be fine

And after entering the unlock code how do you proceed to unlock the bootloader? Please remind the code just allows to enable OEM unlocking which just allows to unlock the bootloader and does not unlock the bootloader itself.

[ottpeter]

I click on OEM unlocking in Developer options, I think that was my last action.

[yvmuell]

As I said, thats not unlocking the bootloader…

Manage the Bootloader

[ottpeter]

fastbook flashing unlock does not work. Before step works. It reboots to FastBoot Mode.

While in normal OS, it can list devices with adb devices, but when in fastboot, it can’t.

[yvmuell]

adb devices for sure doesnt work when in fastboot mode. So what happens with fastboot devices? What system is your PC running, windows or Linux?

[ottpeter]

Windows 10
fastboot devices is empty list.

[yvmuell]

Ok so either its the cable or the fastboot driver, how to update those see here

How to: ADB/Fastboot (Windows)

Platform Tools runterladen von hier Zip Ordner entpacken Entpackten Ordner öffnen, den darin enthaltenen Ordner auch öffnen In diesem Ordner: Shift+rechte Maustaste drücken und Terminal Eingabeaufforderung/Powershell öffnen Wenn das FP im Fastboot nicht erkannt wird: Kann es am Kabel oder USB Port liegen, meist ist es aber ein Fastboot Treiber Problem (unter Windows). Um den Treiber zu aktualisieren: verbinde das FP im Fastboot Modus mit dem PC, gehe zu Windows Updates, suche manuell nach Up…

[ottpeter]

No, it’s freshly downloaded fastboot.
And other cable also doesn’t work.

[yvmuell]

Downloading fastboot isnt what I meant, what I meant is the driver on your PC

@yvmuell

fastboot driver problem (on Windows). To update the driver: connect the FP in fastboot mode to the PC, go to Windows Updates, check for updates manually, go to Optional Updates and Drivers and install everything regarding Google/Bootloader (e.g. Kedacom/LeMobile).

[ottpeter]

I managed to unlock the bootloader on a Linux machine. Now I’m at step 5.
https://wiki.lineageos.org/devices/FP4/install/#flashing-additional-partitions

[ottpeter]

I installed LineageOS Recovery, now I’m downloading OS image and will try to flash with fastboot

[ottpeter]

It worked, I managed to install LineageOS.
Thanks for help!

[skeller2102]

Sorry for the late reply. That it worked with Linux proves my experience.
I also had this problem using Windows 10.
I then updated the USB drivers of Windows 10 as described on

Manage the Bootloader

→ Part 2: On your computer (Windows and macOS)
→ Prerequisite for Windows - Update USB drivers
After this, the command fastboot devices worked.