xiaomi 12 bootloop

So, here's the detailed situation:

the phone's not new, it has a bit over 2 years, but it worked completely fine until yesterday evening (i'm in italy, so it's 10 AM now). I was scrolling instagram reels when i decided it was late enough and wanted to sleep. But when i tried to set teh phone on standby, it instead went to the shutdown menu (or whatever it's called) and after a few seconds, it started rebooting. It instantly started a bootloop.

NOTHING works, the recovery menu is accessible, but for a single second, and there is no option that works. Same thing for fastboot, but since it lasts only a second or two, i only see the orange word "FASTBOOT", before the phone reboots itself. Same thing if i keep pressing, but i just don't see the logo.

i tried connecting it to my pc to try and solve anything, but it can't connect, because it reboots so fast.

the phone has never been in extreme conditions and never overheated, there shouldn't be viruses or malware, since i did a scan 1 week ago and didn't download anything in that week.

I don't have access to the battery, because i don't have the tools to open the back without damaging anything.

i tried letting the phone deplete the battery, but i wanted to sleep, since it was already 2:30 AM, so i left it with a bottle of cold water on top (i didn't have anything else to keep it cold for a long time, and everyone else in the house was sleeping, so my options were limited). However, it didn't solve anything, and the phone's still suck in the bootloop.

I want to many websites and asked many AI, and i didn't find anything. I also looked at other discussions about bootloops, but everyone else had a way to access something that worked, like the recovery or even the safe mode, while i can't do anything directly on the phone.

Please help me, i'm desperate.