https://forum.xda-developers.com/t/...993151/page-145

eliransin said:
Sanzium - hope you or anyone else who is reading this can help me, I am quite a newbie in this. I did it several times with different roms/devices but all went smoothly until now. I tried to flash the rom with the newes FW (MIUI 12.0.3 global and with a downgraded FW to the one in the original post) in both cases my phone went into a bootloop.
I did exactly the following (after unlocking the bootloader and enabling dev mode):
1. Flash TWRP through fastboot.
2. wipe -> factory reset + wipe data.
3. advanced -> sideload
4. sideload 11.0.9 FW + wipe-> factory reset + wipe data (tick wipe dalvik and cache)
5. sideload PixelExperience (with wipe dalvik and cahe ticked)
I performed it once with step 4 and once with a clean fresh stock rom of MIUI 12.0.3 without step 4.
In both tries the device went into a bootloop - what did I do wrong?

I am whiling to take a shot in building PE for MIUI12.0.3 (latest FW) but I will probably need some pointers as I have never cosumized an android rom before nor I know if the build would matter without
FW reverse engineering.
Thanks,
Click to expand...You probably need to format /data, specially if you are coming from MIUI.
What I always do when flashing Cepheus is:
1. Transfer files to internal storage
2. In TWRP: wipe > advanced > tick system, data, cache and dalvik
3. Flash firmware
4. Flash ROM
5. Flash Gapps
6. Format data and reboot
I usually only flash Magisk after first boot

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所以說 從最新的MIUI 12.0.3 global Mi 9 必須刷回 PE 當時的 firmware.

或著等更新的 PE 出來.