For OnePlus 8/8 Pro & 8T/9R
Prerequisites:
Required firmware for OOS13 based builds:
8T: F13 or newer
9R: F19 or newer
DO NOT SKIP THIS!
If you are going to dirty flash from OOS12 based build, you need to update your firmware first. Wishmasterflo has made a firmware flasher that checks the RAM type for you and flashes the firmware to both slots. You can download the firmwares from here:
For OOS12 based build the required firmware is C.33-C.36 IN BOTH SLOTS! DO NOT SKIP THIS!
8 / 8 Pro users can dirty flash from OOS12 to OOS13. The required firmware is included in the ROM.
Working brains, common sense, lots of coffee
Latest platform-tools
Developer options enabled: Settings -> About phone -> Tap Build number at the bottom seven (7) times
ADB enabled: Settings -> System -> Developer options -> USB debugging
Required images: boot.img, vbmeta.img, vbmeta_system.img and recovery.img (put these in the same folder with platform-tools)
Get images from sourceforge
ROM zip (put it in the same folder with platform-tools)
Unlocked bootloader
noteIf you are currently on OOS11 it's better to unlock bootloader before updating to OOS12. For unknown reason some devices cannot be unlocked in OOS12.
Reboot your phone to fastboot mode
Open cmd and go to the folder where platform tools are (DO NOT USE POWERSHELL!)
Enter following commands by copypasting one by one:
fastboot flash boot boot.img
fastboot flash --disable-verity --disable-verification vbmeta vbmeta.img
fastboot flash --disable-verity --disable-verification vbmeta_system vbmeta_system.img
fastboot flash recovery recovery.img
Reboot your phone to recovery mode, click "Install update" -> "ADB Sideload"
In cmd enter command:
adb sideload Nameless-AOSP_xxx.zip
Wait until your device shows Step 2/2 and back arrow appears. Click back arrow, then click "Factory reset" -> "Format data/factory reset" -> "Format data"
infoProgress on your pc will stop at around 47%. It is normal behaviour. Click back arrow in recovery, then click "Reboot to system"