My Ti Book M8407 667 Mhz SNQT15101FLY1 has the following, consistent symptoms.
If I hold the power button on at length, there will be one long tone, followed by flashing white led, followed by the normal boot chime, followed by a black screen. I also hear the hard drive spinning up, or trying to. The battery is good, the PRAM battery shows 3+ volts? The charger light is green. Zapping the PRAM doesn't do anything.
What do you think?