Have you tried holding the power button down to bring up the factory menu?
Press the power button (1 beep when it comes on) hold the power button (1 more beep to reset the Audio/Video settings)
Your PS3 may power cycle or turn off with the next beep if it does press and hold the power again until you hear the double beep.
Selection option #3 this number will NOT erase any of your data.
If this doesn't work take it to someone knowledgable about repairs see if they can diagnose it for you.