[Android Q&A, Help & Troubleshooting] mrmazak:
Soon........

There is no need to root prior to flash gsi. Fact, you should be on 100% stock firmware+ unlocked bootloader, then flash gsi system.

The gsi rom is likely to be pre-rooted Anyway.

1. Unlock bootloader

-Enable oem unlock from settings menu and enable USB Debugging, under the developer options menu

-Reboot phone to bootloader, easy method is with adb. With phone plugged into usb on pc

-ensure you have adb and fastboot installed on PC. (not going into details on this, do google search if needed)

-connect phone to pc with usb cable. Open cmd window (if adb/ fastboot is not installed system wide, then cd to the working DIR)

-Enter the following cmd

adb reboot bootloader

-When phone boots to the fastboot screen(black screen with small font in lower corner "FASTBOOT MODE")

fastboot flashing unlock

--there should be a confirmation message on phone screen. Saying press volume up to confirm unlock, down to cancel.

--Press volume up to continue

** I find it to be best safe practice to allow phone to reboot, or command it to reboot after this step. **

**if device does not automatically perform a reboot, **

fastboot reboot

-Reboot again to fastboot

2. Flash VBmeta(to remove verification)

-Power_3 has three vbeta partitions. One is used to verify System(vbmeta_system), one to verify Vendor(vbmeta_vendor), and one to verify boot, recovery, dtbo, and ironically it verifies the other two vbmeta files

- We will need to flash disable verity to at least 2 of them.

-These are the commands to disable verification

- You will need to download stock rom from Umidigi to get the vbmeta files, that match the

- stock rom you have installed.

-OR You could also pull these files from your device (IF you have it rooted), But having magisk installed before gsi 'may' cause issues.

-To pull vbmeta partitions from device, you need abd and a rooted device.

- Notice the double and single quotes in the following cmd

adb shell "su -c 'cp /dev/block/platform/bootdevice/by-name/vbmeta /sdcard/vbmeta'"

adb shell "su -c 'cp /dev/block/platform/bootdevice/by-name/vbmeta_system /sdcard/vbmeta_system'"

adb pull /sdcard/vbmeta vbmeta

adb pull /sdcard/vbmeta_system vbmeta_system

- Now you have the stock files that are needed to flash the -no verity with

fastboot --disable-verification flash vbmeta vbmeta.img
fastboot --disable-verification flash vbmeta_system vbmeta_system.img

-If you need to // Are going to try and modify vendor( I don't recomend unless you know what you're doing)

-You may also need to flas no verity to vbmeta_vendor

3. Flash GSI

-Due to googles mess of naming device modes. There may be multiple 'fastboot' modes. The fastboot mode from previous steps is the 'bootloader fastboot' mode.

- To flash the system partition inside of the super partition, I found it suggested to make sure you are in 'recovery's fastboot' mode.

-There is more than one way to switch modes, apparently. Since you are already in 'bootloader fastboot' , easiest method will be with this reboot cmd

fastboot reboot fastboot

-Now flash the GSI system

- change the following line to match the file name of the gsi image you are to flash

fastboot flash system xyz-specific-gsi-.img

-Now you will need to wipe phone to use new GSI

fastboot -w

-Then reboot to android and enjoy

fastboot reboot

-Enjoy your gsi rom