MacbookPro continuously beep after start and don't come up
I have a Macbook Pro early 2008 15'' and now for some reason when starting, it sounds a continuously beeps (3 beeps with pause of 3 seconds in between)
while beeping, the sleep indicator light is blinking. The battery is fully charged and no problem according to its indicator leds.
Any help?
MacBook Pro, iOS 6