I recently had problems with my toshiba satellite c55 not rebooting. I tried the whole remove battery, hold power button for 30 seconds, put battery back in, plug in, turn on thing-didn't work. My problem did seem a bit unique though. When I plugged it in and tried to turn on, every few seconds it would sound like it was gonna start, and then didn't. So what what I ended up doing was getting a screw driver and opening the compartment that (I think) has the fan (it's the only openable compartment back there via removing one screw) and it was super dusty in there. I dusted it off, put it back together, clicked the power button, and bam, a miracle.