PS4 turns off after about 5 minutes, but only with bottom case on.

Hello guys. I have an interesting problem with my PS4 fat console. After routine cleaning it will now shutdown automatically after about five minutes but, curiously enough this problem happens only if the bottom case is attached. With the bottom case disassembled and PS4 laying upside down it can work for hours without any issue.

My guess is I somewhat screwed up the metal on the case or the screws that are responsible for grounding the console and some sort of short circuit happens? What reinforces my theory is that indeed there are slight burn marks on the grounding screws (the triangles attached to the phillips screw)

A followup question: is it safe to use the PS4 without the bottom case? Will it overheat?

Any help is greatly appreciated.