Holy shit, the PS4 just turned on this time!
Currently slowly doing the usual checks, like when the system gets turned off by getting disconnected from power.
I also removed some dust (which I have to admit, was a bit more than I expected) from the vents/holes. Maybe it was too much and the system really just did overheat? I mean, this sweet baby runs like 18 hours every day, and I own it since Day 1.
We are all getting old and tired.
It's done with the system check now. Everything works so far. Trying Dragon Ball now.
Thanks to everyone who helped, made memes, or just helped by sending some genki energy to my PS4 Pro.