I have the same problem. My mother completely depleated teh battery and left it off the charger for days. The battery is completely dead. No problem, right? But when I connect it to the PC or to the AC adapter, it REFUSES to come on, refuses to charge and is not recognized by any computers. It's basically dead but nothing has been physically done to it. WTH?
I've already run through the normal attempts to reset it: Play/Pause + Menu. Menu + Select. Connecting it to the AC Adapter and holding Menu + Select. Connecting it to the AC Adapter and holding Menu + Play/Pause. Still no signs of life and it won't charge. I left it connected to the AC Adapter ALL NIGHT and still it won't turn on, take a charge... nothing. Please, can anyone help??