power supply. check your fuses in the cabinet. you might get lucky and have just blown a fuse. usually the game the monitor and the light all are fused separately.
if that's the case... BEFORE you go all crazy and wrap that sucker in tinfoil and jam it back in there, you'd best replace that fuse with a proper sized (or even slightly under sized but NEVER OVER SIZED )one and try it again. if it blows again, you have a serious problem that needs attention.