Yeah, i know. Had it with my mobile sometimes due to a software bug (its a sony-ericsson).
The battery wont respond to anything for a while. It is to keep those Li-Ion / Li-Poly baterries from exploding...

But i was still able to press the powerbutton, the nokia logo came up an when no charger was conected even the Backlight went on! So no *completly* dead battery.

And, as mentioned, the device seems to charge for a minute or so (with the nokia logo on screen, but no Backlight) and then seems to do kind of a reboot. The PC even recognices the device as conected, so some parts seems to be booted up.