One of my friends purchased a Redmi 12 5G from UAE. After getting it he found out that banking apps doesn't work and that his bootloader was unlocked. Long story short that device was Chinese variant with global rom. After looking at some video on YouTube he somehow managed to lock the bootloader with MiFlash tool.
Now his phone is soft bricked. It boots to bootloader now. I don't really know what is happening but guessing it's some AVB issues or alike.
He have downloaded a Chinese rom now. But I don't really know what to say to him. I don't think you can even flash the stock rom in Xiaomi devices. Not sure if MiFlash would work with locked bootloader. I can't even try those methods as I don't have the phone with me. I don't know of I can flash the firmware in EDL, I can't find the firehose file online. (Chipset is Qcom SM4450).
Another thing the device were in MIUI 14. And had a Xiaomi account. But didn't couldn't add the device in Mi Unlock Status as the BL was already unlocked.
So my questions are
1. Can I flash the stock rom with fastboot or MiFlash
2. Are there any EDL tools supporting this chipset so I could flash the firmware
3. Can I unlock the bootloader using MiUnlockTool or XiaoMiToolV2