With the computer plugged in and the battery installed, I press the power button, the power indicator (next to the hard drive indicator and battery indicator) will flash green for about 1/2 a second, and that's it. No fans will spin up, no optical drives will do anything, nothing.
I took the battery out of the computer and ran straight A/C power, same symptom.
I let the battery charge overnight, and the battery indicator was green while the computer was charging.
One suggestion was to get a new battery, since Dell's won't even power up with a dead battery. However this does not make sense, because if the battery is removed, shouldn't the computer at least start?
I reseated the two RAM modules, and pulled out and pushed back in the hard drive.