XDA thread: https://forum.xda-developers.com/t/op8pro-oos-11aa-ba-da-unbrick-tool-to-restore-your-device-to-oxygenos.4084953/

Specific notes:

When using Android Q MSM tools, backup your /persist as a precaution to prevent loss of fingerprint sensors. You need to root your device and use dd if=/dev/block/bootdevice/by-name/persist of=/sdcard/persist.img should you wish to do so. If you failed to backup this partition which is unique per device, you may want to follow instructions at https://forum.xda-developers.com/t/guide-fix-persist-img-loss-of-finger-print-sensor.4126455/ to recover your fingerprint sensor.