[Android Q&A, Help & Troubleshooting] Codefoo:
Thanks /Umidigi Power3 Rooting

Thank you! XDA and those who POST

*NOTICE: THIS WAS DONE USING LINUX.

[Preface]

Problemo

Already unlocked bootloader, but first time was just:

$ sudo fastboot flashing unlock

which was not sufficient. I also had to run:

$ sudo fastboot flashing unlock_critical //This was necessary for me.

I was stuck in bootloop. Scared. XDA Held my hand.

I tried the, googled, tutorials and mustve done something wrong. Or maybe not?

I found unofficial TWRP, and attempted the recovery.img flash. It claimed to work just fine, but when run

$ sudo fastboot boot recovery.img

it failed miserably and spun me into a downward sloping bootloop, and having no connection to PC at all.

I bootlooped infinitely.

as the phone bootlooped, I panicked some more while searching and found STOCK_ROM for my device from UMIDIGI COMMUNITY

I panicked for an hour or more, 300$ phone down the drain.... dont have this money to burn right now

I couldnt get the bootloop to stop... The phone would not power down or respond to Power+VolDwn.

I panicked some more..

[Solution]

BEER!

& Prayer.

I learned, with the Power3 if your hold Power+VolumeUp it will power off indefinitely.

.....and I mean HOLD it-- I must've held it for at least a minute.

Now when I Power on, I hold VolumeUp and it brings me to a small (almost unseeable) menu, scrolling from:

[Recovery] <=

[Fastboot]<=

[Norm] <=

After many times of failing to select fastboot, because of holding VolDown.

FINALLY! I was able to select the system into Fastboot and receive a signal via USB from my phone to PC.

[NOTE]: VolumeDown is SELECT! (Not the usual PowerButton)

Now armed with the STOCK_ROM, unziped, and a little bit of fear I decided:

STOCK_ROM (UMIDIGI_Power_3_V1.2_202003281108.zip)

[Is actually newer than the STOCK_ROM shipped with the phone]

Im gonna flash the STOCK_ROM, recovery.img and pray it works!

With my phone now in fastboot mode, computer recognizing it:

Open terminal, cd into folder holding STOCK_ROM unzipped

$ sudo fastboot flash recovery recovery.img //again this is from STOCK_ROM

$ sudo fastboot reboot

[NOTES]:

***********MAKE SURE IT IS PROPER DEVICE MODEL *************

I first used MT6567 and was stuck in bootloop again where i required MT6771. What happened my first attempt is that I took a TWRP from a different CHIP(MT6567). Seems like they're incompatible. Who knew? =HAHA=

This allowed my phone to reboot.

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-------------------------[ THANK YOU XDA MY PHONE IS NOT A 300$ PAPERWEIGHT! ]--------------------------

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Now I still wanted to ROOT my phone, and later install LineageOS

To tackle my ROOT: [YES THIS WORKED!]

now that the phone boots into android os,

[1] :: enable dev mode, enable usb debugger, stay awake

[2] :: use a terminal on PC while connected with USB:

$ sudo adb devices

should show your device, now:

$ cd /into/your/STOCK_ROM

$ sudo adb push boot.img /sdcard/Download/.

now boot.img is on your device inside /sdcard/Download/

[3] :: Using the guides for Magisk, I patched the boot.img from the STOCK_ROM --- this was done using the UMIDIGI Power3 device and MagiskManager.

[NOTE]

Using MagiskManager, It indicated that MagiskManager was installed but Magisk was not installed.

Tapping on Install for Magisk prompted me for two options ...I cant remember the two, but the one I selected was to use a file from the device.

[INSIDE MAGISK MANAGER ON THE DEVICE]

[3a] :: Tap/Click Magisk INSTALL (on the device, using MagiskManager apk)

--and select file from device, locat:

/sdcard/Download/boot.img (the one just put there in step[2])

Magisk will now patch the boot.img and output, into

/sdcard/Download/magisk_patched.img

[3b] :: Back to PC:

same terminal:

$ sudo adb pull /sdcard/Download/magisk_patched.img .

Now,

../magisk_patched.img

will reside inside /STOCK_ROM/ folder.

[4] :: same terminal:

$ sudo adb reboot bootloader

$ sudo fastboot devices (just to check your device is present)

$ sudo fastboot flash --disable-verity --disable-verification boot magisk_patched.img

$ sudo fastboot flash --disable-verity --disable-verification recovery recovery.img (STOCK_ROM RECOVERY)

$ sudo fastboot flash --disable-verity --disable-verification vbmeta vbmeta.img (STOCK_ROM RECOVERY)

$ sudo fastboot reboot

*vbmeta.img is important to flash. I learned this the hard way :)

vbmeta.img is used to verify boot meta before booting, not sure exactly whats in this file but I think it does some initial Power On Self Test Boot checks.

Im assuming in the existing vbmeta.img it gets written and changed from STOCK when you boot. So the first time I tried all this, I didnt want to use the vbmeta.img as I thought it may bork it. Actually not flashing it borked it. As I said earlier, my STOCK_ROM was not the same version as the STOCK_ROM obtained from UMIDIGI Community, so I wasnt sure of any new problems I could be creating.

[Profit][COMPLETE!]

OMG! It worked for me!! I followed those steps and completed my ROOT.

Now.. I just gotta figure out how to install LineageOS ---

Thanks for reading, I hope i cleared some things up -- as I was very confused myself.

##### PAY IT FORWARD ######################

# I always used XDA to save my life, but never did I post.

# When I was stuck or stranded, or a friend needed help.

# XDA was always there, they never asked me for anythin

# Now I decided I would do what I could to return the

# favor.

#

#

# Thank you all, you are the very best of human beings!

#