[Xiaomi Mi Note 10 Questions & Answers] ZINHAR:
I have a CC9 Pro Premium. Even if i can't fix my problem, hopefully this story will PREVENT people from messing with their IMEIs... I hope no one ever goes through what I just did

I'm obviously by no means encouraging changing IMEIs, even in certain 3rd world countries where it could be necessary!

So here's a detailed backstory: When you purchase a phone where I live, you need a valid passport in order to pay tax and register it's IMEI number, and if not you get cut off by your operator within a month.

I didn't have one, since it also takes about 4-8 months to process, and I couldn't even preform a request due to the corona virus situation.

So, being the ignorant idiot I am, I thought it would be a great idea to change it's IMEI number till I can register the original one, since a lot of people do this over here apparently, white market

I followed a tutorial I found online (And re-posted on XDA, so there's nothing really wrong with it), and here's what happened:

(Root, TWRP and Diag is OK in all steps)

I made a .qcn backup using QPST build 480, saved the original somewhere safe, edited the copy, wiped modemst1, modemst2 and fsg, then restored it

*phone reboots*

Everything's the same, and still getting reception, no change

Took another backup and saw it was the same, so I give up

The next day I try again, but this time is when the problems started... I take another QCN backup just to be sure, and it's slightly larger (Could be because I just inserted a 2nd SIM for the first time right before it), edit it, then wipe modemst1, modemst2, fsg and this time: "fsc" since I saw someone do it in another tutorial for the Mi Note 10

*phone reboots*

*boot animation*

*resets and goes to recovery*

I was shocked. I wipe the 4 partitions again and the phone boots normally, nothing has changed (apparently).

So I put my SIMs in and go watch a movie. Then I switch it on, only to see there's no reception!!!

I wipe the partitions, and restore the first original backup... boots to recovery again...

Wipe... Boots normally... restore the 2nd original one (slightly larger, both sims)... boots to recovery...

Then I just decide to miflash a fastboot rom, maybe that will get things back to normal!

So I wipe, flash rom... IMEI and Baseband now Unknown... Yikes...

I next find an xQCN backup online for the Mi Note 10 that only has a single IMEI in it, that belongs to the 2nd sim (SIM 1 550 only, QCN View, the 1st 550 missing)

Replace it with my original and reboot, IMEI 2 and baseband is back! But no reception, even after multiple reboots...

I wipe partitions again, IMEI 2 is still there... Interesting...

I continue trouble shooting, even: wiping the partitions, restoring the original backup, flashing fastboot rom... still boots to recovery (Mi Recovery of course), setting 755 permission for modem files...

------------------------------------------------

SUMMERY:

I need to find out why the original backup keeps booting to recovery!!! Also some information about "fsc" partition would be nice, since wiping that probably started the whole issue (Is it a backup for fsg?!)

Important things I discovered:

1) Wiping modemst1 and modemst2 at the same time is enough for the phone to boot

2) The reboot to recovery (Recovery loop?) with the original backups is caused on an OS level, because one time it took so long that I even saw the lockscreen for half a second before it rebooted (no SIMcard in the phone either)

3) After hours of dorking I found 2 other similar instances that could be related:

https://xdaforums.com/zenfone-2-laser/help/help-donor-qcn-file-ze550kl-z00ld-ww-t3520647/page4 (Page 4-5)

(Normal boot using a custom rom?? Interesting... maybe Xiaomi.eu made no difference for me because it's still pretty much just MIUI)

https://www.youtube.com/watch?v=8Ym0FP4BkY0 (The bottom comment):

"We cannot repair both SIM slots.

We can only repair SIM2 slot for IMEI repairing. After IMEI repair process, SIM1 IMEI getting '0' value. When we are trying to repair both SIM slot phone is entering the Bootloop and entering the recovery mode(twrp). Thats why we are remove SIM1 IMEI from qcn file and this time we can will repair to SIM2 slot. Do you know this Problem ? What can we do to solve this problem? Thank you in advance for your help."

Regards, and many thanks... DON'T MESS WITH IMEIs!!!