I cannot say for sure since I don't have it on my bench to test and confirm, but I think your laptop is suffering from one of the following:
- Intermittent backlight unless you are sure the laptop is definitely shutting off completely, not just switching off the light of the screen (flash a light behind the Apple and see if something appears on the screen).
- Intermittent shut off from overheating, needs cleaning and/or new CPU heat compound and/or new heat sink and/or new fan.
-
- Intermittent power failure due to a bird level issue: failure of some component that intake power from main power rail and produce secondary yet critical power rails.
+
- Intermittent power failure due to a board level issue: failure of some component that intake power from main power rail and produce secondary yet critical power rails.
- Intermittent GPU failure in which case it is better to have it replaced as the cost may exceed the cost of a new/used board.
I cannot say for sure since I don't have it on my bench to test and confirm, but I think your laptop is suffering from one of the following:
- Intermittent backlight unless you are sure the laptop is definitely shutting off completely, not just switching off the light of the screen (flash a light behind the Apple and see if something appears on the screen).
- Intermittent shut off from overheating, needs cleaning and/or new CPU heat compound and/or new heat sink and/or new fan.
- Intermittent power failure due to a bird level issue: failure of some component that intake power from main power rail and produce secondary yet critical power rails.
- Intermittent GPU failure in which case it is better to have it replaced as the cost may exceed the cost of a new/used board.