The Restoring of Bricked OnePlus 8 Pro

The Appear of the Error

1. I received the OTA update from OPPO which allowed me to upgrade the current ColorOS 12.1 to ColorOS 13.
   
   
2. I unpacked the update, installed Magisk to another slot as usual and restarted.
   
   
3. Having no awareness of what I have done, I found that the reboot process was interrupted. After the OnePlus logo page, the system entered the bootloader and stuck in it. Neither rebooting nor entering the stock Recovery could solve the problem.

The Exploring of Solutions

1. First I thought that maybe flashing the TWRP and remove the Magisk conponents in system directories could work, but when I found the TWRP images, they were not even compatible with Android 12 and made the recovery of my phone totally destructed.
   
   
2. Then I was seeking for the unpacked full images of ColorOS but nothing was found. OPPO had a strong control of the ROM and no unpacked image could appear on Internet.
   
   
3. I finally gave up and started to seek for other's help.
   
   
4. I went to the OPPO Customer Service next morning, but the staff told me that their only policy due to this situation is force restoration of the whole storage, including /data and /sdcard partitions. I was extremely upset listening to this and left there.

The Help of Friend

1. Back home, I told all of these to a group of friends, and one of them, Uebian was willing to help.
   

2. We first found a suitable Third-party Recovery, which was Wishmasterflo/device_oneplus_opkona. Then uses

fastboot boot <img name>.img

to boot into recovery. The command must be run in bootloader mode, which can be entered by pressing on the Power button and the Volume Up and Down button. Then run

adb shell

to enter the shell interface of the phone, like the ssh connection.

3. Then use the command below to check the current slot. Remember to switch to the slot with new system installed.

fastboot getvar current-slot
fastboot --set-active=<a or b which is your installed slot>

4. Extract the latest image of the system with tobyxdd/android-ota-payload-extractor and get the boot.img and recovery.img.
   

5. Use the command below to test the boot.img to see if it can boot into the normal system.

fastboot boot boot.img

6. I successfully entered the new system by this command. So I re-entered the bootloader and ran this to permernently flash the .img into the phone.

fastboot flash boot boot.img

DON'T FORGET THE boot IN THE MIDDLE!

7. Finally restore the Official Recovery.

fastboot flash recovery_a recovery.img
fastboot flash recovery_b recovery.img

8. Reboot into the system.

Frequently used commands

adb devices
fastboot devices
fastboot reboot //reboot into system
fastboot reboot bootloader //reboot into fastboot mode
fastboot reboot recovery //reboot into recovery