Hi, I'm kinda stuck at the 1. Step already, System-Update just says "Update Installation failed." when trying to install the A12 Beta.Here is a lengthy way to get this working on a EU 9 Pro with WORKING SIM card. I just completed my first phone call! Only do this if you know what you are doing and if you are familiar with the concepts of flashing ROMs, using fastboot to flash partitions and possibly using the MSM tool to restore your device in case something goes wrong. I told you.
Steps to switch from OOS>COS on non-chinese OnePlus 9 Pro. Credits to: Telegram user SamuraiTronVC
Note: This whole process will wipe your data.
1. Install Android A12 Beta 1 by OnePlus via Local Upgrade.
2. Once booted into A12 Beta, install the custom Local Update APK that they provide.
3. Install the ColorOS Dowgrade package and reboot.
Here is how to fix the missing network on 9 Pro. I tested it with my own LE2123 EU 9 Pro, but since the A12 DP is working on IN and NA versions as well, should work for everyone. I updated to the latest ColorOS build after step 3, A.08. Don't know if that is required, but do it anyways. The phone has been behaving a bit weird after doing this - e.g. boot loops once, but then it works etc. Not sure if it has to do with steps 4-6, but proceed with caution. Credits to: Myself.
4. Extract the modem.img from the A12 DP using Payload Dumper. I did it already and you can download it here, but feel free to extract the .img yourself.
5. Unlock your bootloader:
fastboot oem unlock
6. Flash the modem.img:
fastboot flash modem modem.img
Is there any specific OOS Version I have to be on? I tried on 18.104.22.168 and 22.214.171.124 but both times it fails with the error above.
Thanks in advance. ^^