OS Tried:
Windows 10 Pro
Arch Linux (with usb udev rules)

What Happened?
Plugged in my Redmi note 9 with unlocked bootloader, usb debugging enabled with security features disabled.
Flashing went well, firmware was flashed, then it was stuck on "ADB is waiting for devices" and the device bootlooped for some reason.

What can cause the problem?
mostly incorrect image flashed, because when i flashed Engineering ROM for merlin, it did boot, but when I flashed some other custom rom, it didn't(I used the one for merlinx but both are the same). I couldn't get it working and got it hard bricked and restored it using BROM mode.

NOTE
Custom recoveries such as LineageOS recovery, UBports recovery didn't go well, it never went to recovery screen despite me holding the hotkeys
but the TWRP for Redmi 10X went well, it worked, but it was temporary flash, (I just booted from it)

What did I not try to do
I didn't try to flash manually using twrp, but I flashed manually using fastboot by first erasing the partitions then flashing via fastboot mode

What happened next
It still was in a bootloop, lost IMEI due to flashing Engineering rom using sp flash tool but successfully restored using MAUImeta, but now stuck on engineering rom.
Xiaomi never provided a working image of its stock rom via its website, its servers are painfully slow and made me wait 3 days but it didn't work

What help do I need?
I need to somehow flash a working UT image and make it work

@Vlad-Nirky Well it works 🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳
But the sim still doesn't work sadly. Its more of my mess which I did. Thanks for the community, especially @Vlad-Nirky @MrT10001 for the support......

@Vlad-Nirky Nah, they don't. atleast i have a working UT phone, after 3 months of effort, dropping my battery life by 60% and hopefully gain some knowledge with Mobile Linux, I've been a desktop linux user for the past 6 years and now i got the opportunity to flash it into my mobile phone. Thanks for the community for that....

@Vlad-Nirky They actually don't, one of the technicians said that i need to write both IMEI's then calls will work. I'll try it today and tell you the results......

@Vlad-Nirky Well it works 🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳🥳
But the sim still doesn't work sadly. Its more of my mess which I did. Thanks for the community, especially @Vlad-Nirky @MrT10001 for the support......

@Vlad-Nirky My kernel version right now is 14.4.186. I am on android 11
Will it work

@Vlad-Nirky
Yep, and i wrote only sim2 and inserted only one sim in sim2
I use a local BSNL provider (the modem and frequencies are different in india so i couldn't get it working in global firmware)
Android 12
Yep, i used the initial imei linked, i have the original imei values (i knew i would mess it up so i took a photo before flashing UT)
And no, i didn't change IMEI....
the root cause is simple, the global frequencies are different and indian ones are different, hence since i flashed the global frequencies, i couldn't get it working.
Thanks for the reply....

@MrT10001 @Vlad-Nirky I followed this video. it worked for me.
But i'm unable to make calls via that phone (no mobile network).
Thanks for reply...

@MrT10001 @Vlad-Nirky Can I get manual flashing instructions please?
I'll try my best to flash it manually, but I need your help regarding manual flashing.

@MrT10001 It doesn't work right now.

@MrT10001 I can enter fastboot and flash images, but the images flashed from fb don't work. flashing via recovery mode (and only eng. rom) works.

@Vlad-Nirky I also hope it. I hope he will find a solution to help me out.