I have a blackview A20 which is a low spec phone running android oreo go.

I would like to use this phone for experimentation with android development and learning about android on a cheap device without risk of breaking my main phone. To do this I would like it rooted and as a bonus with a custom recovery so I can test custom ROMs.

State of device:

  • Unlocked bootloader
  • Unchanged ROM
  • Unchanged Recovery
  • OEM unlocking enabled
  • USB debugging enabled

What I have tried:

  • Flashing recovery images with fastboot

    Using fastboot flash recovery recovery.img with some TWRP and CWM recovery images all yield:

    target reported max download size of 134217728 bytes
    sending 'recovery' (4690 KB)...
    OKAY [  0.169s]
    writing 'recovery'...
    OKAY [  0.276s]
    finished. total time: 0.448s

    or similar. Then I restart phone and select boot into recovery mode. The phone hangs for a small while before restarting and booting into the normal OS. On restart into recovery the unchanged recovery is there still.

  • Various 'one-tap' methods

    All of which were unsuccessful. If needed I can give details.

  • Installing SuperSU zip from recovery

    In a futile attempt I tried to use the android recovery to push a SuperSU zip with its update from zip option. I knew this wouldn't work but I found something interesting. On the Apply update from SD card option I get an error saying couldn't mount /sdcard

  • Booting recovery images with fastboot

    I have tried the fastboot boot recovery.img command to try to boot directly into the images. I get this

    downloading 'boot.img'...
    OKAY [  0.211s]
    OKAY [  0.047s]
    finished. total time: 0.261s

    output but the device just restarts and boots normally into the normal OS.

What I would like from this question (In order of importance):

  1. A way to root the device
  2. A way to access a custom recovery (even if temporary)
  3. Ability to install custom ROMs
  4. A permanent custom recovery
  • First thing to look for is whether there's a custom recovery (e.g. TWRP) available for your device. You'll need that anyway. If there is, get it (installed). Then take a look at Magisk. Take a look at my article Root for all: Magisk to get an overview. – Izzy Jun 12 '18 at 22:51
  • @Izzy I thought so, I can't find a custom recovery anywhere for my device. One of the recoverys I tried was the generic arm twrp and you can see the results of that in my post. Getting a recovery is the main problem I'm having; I'm fairly confident rooting after that. – Jake Jun 12 '18 at 23:01
  • Have you tried TwrpBuilder? Claims to generate a TWRP image from your stock recovery. I haven't tried it so far (I always check those things before I buy a device, to make sure TWRP and custom ROMs are available or the latter at least already "in the make"). That way I can root the device before unboxing :) (very first thing: unlock bootloader (no data to lose yet), flash TWRP, and only after that switch on for usage). – Izzy Jun 13 '18 at 5:59

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