Phone with issues, want to discern if hardware or software


Apr 29, 2019
I have a Mi 9 and yesterday it did some weird thing, as it rebooted itself twice in a row at mid day and by afternoon it shutdown itself to being completelly unresponsive. The phone appeared dead as I couldn't power it on, nor bootloader/fastboot. Also connecting the charging cable didn't do anything (no light nor charging animation).

I left the phone unplugged for the night and this morning I was able to charge it up, the led blinked quickly, as if the battery was completelly drained, but it end charging it and I could start it without issues, but right now it has just rebooted itself again for no aparent reason and its back online, but not sure for how long.

Checking the forums/internet, this issue seems to be related with the battery or motherboard in some cases, but it isn't very clear on why does the phone do that. Most of the cases where dropped phones or some water was dropped and so on, but in my case I haven't done anything like that, which makes me skeptical on why could a phone fail if no hardware issue has happened. So I'm writting this post to see if anyone knows any test or procedure I could try to rule out a hardware failure, since I want to discern if this issue could be fixed by software (flash stock, reset, etc) or its a hardware issue.

TL;DR - Phone rebooted by itself and it seems to be a little unstable in the past 72h, do you know a way to check if this issue its hardware or software based?

P.S.- When I'm talking about software, I don't mean ROM by itself, but some corruption or stuff that might happen under the hood by the apps or usage of the phone, like when you're on bootloop after an upgrade and doing a factory reset solves the issue.