Thank you all who contributed.

I was hoping for some log that could maybe save some info when in a hurry, sensing an eminent crash or an emergency, but that doesn't really make sense, does it? - If it crashes, it crashes. There's probably no time to dump anything to disk. Otherwise the crash would have been prevented.

Anyway, some paths have been opened for when I have time to dig in a little bit deeper.

I'll quickly find something else to annoy you ASAP. ;-)

Thanks.

I thought there could be some place in logs the system could write error messages to. Even hardware derived.

I've been going through /var/log/* and found thousand of scary messages, but can't really make sense of any of those.

Well... The power button does work to boot the system back up. So...?

It's a small desktop computer Asus VivoMini VM65, not easy to swap parts.

Asus doesn't even have a picture of it anymore. Here's a bunch.