Does it start up at all? Screen backlight lights? No text on screen? Holding power long enough, have to wait, backlight comes on, then a few seconds later the 'power on' displays on the screen? "Wall wart" power supply or plugged in to a vehicle? If you have both can you check the 'other'? No backlight but text on the screen, error message? That will happen when CD card gets corrupt or fails. "Waiting for main unit" message or similar? Check with a different card?