Why is there a black screen when I turn on my laptop?

Question

Computers

1) turns on normally;
2) after reboot it turns on, but the screen is black;
3) after some time (until I figured out which one exactly) it turns on again normally and if you reboot, then again the black screen;

Notebook HP pavilion g7, 2012, most likely overheated repeatedly, because. when first turned on, it gave out 90 Celsius when opening chrome. I changed the paste, but apparently it's in the tube itself, because. it still gets very hot. The laptop came after the repair of the display. There was a black screen even before changing the paste, so I didn’t break it)

Answer 1

if there are two cards, then it can get confused when restarting.
it is necessary to set only some in the bios.
and as for cooling, it may well be that after repeated overheating, the tubes are tired.