I assume he has checked the power settings in "control panel"? If that's no good he can hit "control alt delete" to launch "task manager" and look at the processes that are running to see if there is one (or more) that doesn't belong... or, try to "turn off" from that window, or, one by one, terminate each of the processes, the try the power button to see which one is causing the problem. At some point, it is just easier to pull the battery or re-install windows... It will run without the battery... then pulling the plug is a one step instant power off.
FWIW. Thx, G.