weird intermittent shutdown issues

I've had this laptop for a couple years now. A bit ago i had to send it off to lenovo for unrelated issues, and a couple days after it came back, it shut down completely, and i couldn't turn it back on no matter what. I got on with lenovo support and they sent me through some troubleshooting steps, none of which worked, and they had me send it back for repairs

Apparently once it arrived to the service depot it was working fine and they couldn't figure out what was wrong with it, and sent it back.

This was a month or two ago? Anyway, it just happened again. I was turning it on to search something up, it came on as normal, then immediately started to shut itself down. It appeared to do so in a normal process, just without my input, like the power button went from solid white to blinking for a bit to off. Then when i tried to press it again, nothing could turn it on.

I figured it might be the same thing again so i decided to wait. Experimentally i shook it around a little bit (lmao) not violently, just as much as it would being carried around/in a delivery truck in case shipping shook something back into place last time xD but that didn't work. So i unplugged it, did the power drain thing, and left it for the night. And this morning it is working again just fine.

Does anyone have any ideas what this might be? I don't know how to get the service depot to gaf if the problem doesn't decide to show up when they're testing it