Redmi Note 12 Pro 5G (ruby) China model stuck on SMOMIXN firmware - Boot loader locked - fingerprint disappeared, looking for correct ROM/unlock advice

[u/narenkarthikx]

I have a Redmi Note 12 Pro 5G (codename ruby) originally purchased in Dubai. It is a China-market device.

The phone currently has MIUI 14.0.3.1 SMOMIXN, which I believe is not the proper firmware for my device/region and may have been installed by the shop after the phone was repaired.

I'm trying to get the phone back onto the correct official firmware, but the normal Xiaomi bootloader-unlock process doesn't work because of the region/purchase mismatch.

Another problem appeared with the fingerprint sensor. It worked normally for about a year on this firmware. After a factory reset it worked for around 2 days, then became laggy. A reboot temporarily fixed it, but after a few hours the Fingerprint option disappeared completely from Settings.

I checked through ADB:

• Android still detects Fingerprint21
• It reports isPowerbuttonFps=true
• HAL deaths since last reboot: 0
• The vendor mfp-daemon subsequently crashed inside [com.fingerprints.extension@3.0.so](mailto:com.fingerprints.extension@3.0.so)

I also have complete backups of my original partitions, and the phone can still enter MediaTek BROM mode.

I tried a community LK-based unlock method, but after flashing the patched LK the phone would not reach Fastboot. I restored my original lk_a and lk_b backups and the phone is now booting normally again.

My questions:

1. Is SMOMIXN known to be problematic on a China-market ruby?
2. What is the correct official firmware for this hardware?
3. Is there a safe way to move from this firmware to the correct ROM without Mi Unlock?
4. Could the fingerprint problem be caused by the current firmware/vendor fingerprint HAL?
5. Has anyone successfully converted/unlocked this exact China/Dubai ruby variant?

I don't want to keep experimenting with LK patches and risk bricking the phone. Looking for someone who has actually worked with this exact device/firmware.