iPhone 12 mini stuck in bootloop

Thanks for feedback, Leo. But I'm afraid, mine is not the bootloop where it happens every 3 minutes. The logo just keeps blinking every 4 seconds or so. As you say, it could potentially be a NAND/Motherboard issue, but I hope is isn't. My biggest hope is that it be a module issue (e.g. Face ID, Earpiece etc.) So I could get the phone working just enough in order to make an icloud backup.

Okay... That usually happens when the phone detects a faulty battery. I've got quite a lot of old iPhones that I dug out from my drawers, and most of them blinks the logo without fully booting because the battery is totally dead and won't hold a charge. If the iPhone doesn't detect a working battery, then it won't start and would only boot halfway, flash the logo, and restart. Have you experienced any issues with the battery before this happened, like short battery life? if so, then it might be a dead battery. It's possible, since it is indeed 4 (and almost 5) years old since first released and the battery being miniature doesn't exactly help a lot. I would suggest you to replace the battery first, but if you can find somewhere that accepts refunds in case it didn't fix the issue.

also module issues don't necessarily cause the phone to boot loop like this; the phone would boot up and reboot every 3 minutes like I mentioned, not just restarting before it boots into the system.

Thanks again, Leo. I could take it my local repair store and try to connect a new battery to see if that fixes the issue. (I haven't opened the phone yet) But to answer your question above, no. I never experienced any problems with the battery so far. I also do not recall checking the battery efficiency lately. But what might be useful to know, and why I think that it might not necessarily be a battery issue, is that even though the iPhone is on a bootloop (it's been more than 10 days now) I got the battery low sign (i.e. dead battery - with charger sign) 2-3 days after the issue began, so my guess purely based on this would be, that if it was a battery issue, it shouldn't have even shown this logo. After I recharged it, it went back into the bootloop with the apple logo flashing every frew seconds. But as you say, if it is indeed a battery issue, and if it resolves upon installing a new battery, I would just be so relieved, and happy!

Well, if it does show the battery low sign, then I seriously don't know what the issue is, because normally that suggests a functional battery. I haven't encountered anything like your issue. Once when I was repairing my iPhone 14 with a broken screen, I accidentally tore the battery cables and it boot looped but never showed the charge sign. Right now you might want to take it to a repair shop that knows how to repair a motherboard, and maybe they'll be able to help. Don't send it to Apple, though. They'll only get you a new motherboard.