That isn't what I was asking. I was asking if when it goes black if the computer was on, stays on (heard drive sounds, fans, lights, etc.) if that isn't the case, and it is just rebooting over and over, then it isn't staying on.
Just before this happened, did you do any updating? If yes. Make sure there is no possible way to connect the laptop to the internet. No Ethernet and no WiFi around, and then try restarting it.