[Redmi Note 9 Questions & Answers] MorderczyRealizm:
Hi. On the start i want to apologize for any chaotic description i may give, or mistakes/unclear explanation since for first - english is not my native language and for second i'm terribly tired and depressed as a result of 2 days searching for informations how to solve my problem. Lets get to case.

Patient:

Xiaomi Redmi Note 9 (merlin), complete model "M2003J15SG", it have unlocked bootloader, no root, no custom recovery, probably no granted permisions for adb.

I'm not sure which version of rom it have at the moment i remember only that it was global.

Case:

Few days ago Xiaomi displayed notification about possible upgrade to MIUI 13. That was not the first update that i installed directly just by accepting it, so i decided to give it a go.

After that, my phone went to infinite bootloop (there is a mi logo with "powered by android" that stays there for minute, and then it reboots and situation repeats itself).

Recovery is not working (or i do it wrong -> power+ vol up, maybe it's damaged after this update) i cant get into fastboot either (power + vol down).

However when i connect to pc and press power + vol down windows makes sound of pluging and unpluging device few times (probably its a mode that i can flash it with new rom with flash tool).

If i can (probably) flash whole ROM then what is a problem? :

Main problem is, that i have there very important data there, especially text messages and there is no way i want to lose it.

To give you small tip why it is so important to me i will explain it with a bit of offtopic:

Inside of sms google app i have messages that contains crucial informations, like my ex employer incriminating messages, codes that gain me acess to meds in pharmacy, adresses and so on - i just can't lose it because at the end i could have a pretty big trouble about it, including my ex employer tring to make me a scapegoat for his own decisions in front of a law. End of offtop.

Expectations:

I've so far read that if i will have custom recovery, i would be able to make a backup of data inside of Redmi.

Then i would try to flash entire ROM, but important is that i will have that data backed up.

Since i'm not a master class when it comes to adb, flashing, and so on - i would like to ask you for help.

I mean i know how to flash rom or, unlock bootloader, or root - but i lack knowledge about subjects that matters in this particullar situation,

especially i dont know can i flash only recovery with flash tools, and if so - will it erase internal data,

where to get already prepared scatter and recovery, how to do it - i need extremaly step by step help, so i could understand it and do it.

Is it possible to flash only custom recovery with flashtools without erasing data, and if so - how?

Is it possible to flash ROM without data being erased - if so, how?

Is there any tool i should look into, or maybe when it cames to switching to recovery/fastboot i'm doing something wrong?

Is there ANY and i mean ANY way to or fix bootloop, or at least get custom recovery without permanently losing important data?

Warning:

If you need any more informations - let me know and i will post it.

I've searched with google for 2 days right now and i have no straight answer for a questions.

If i posted question that already was asked - i apologize, truly i am not able to be on highest level of my perception and thats why i would like you to explain things to me like for a 8 years old.

I would appreciate any form of help with a subject. Thank you in advance for a time, knowledge and answers.