My iPod says it's charged, then dies?

Hello,

I left my iPod plugged into my car FM adapter last night overnight. The adapter usually charges the iPod when the car is on, but since the car was off and I forgot to slide the hold button to orange, the iPod seems to have died, since it wouldn't turn on when I unplugged it from the car. I plugged it into the wall outlet for a few hours and now it says it's charged; however, when I unplug it from the wall the gray apple icon screen comes up and then it slowly fades to black/dies. Also, whenever I plug it into my computer's USB port the screen just flashes a very faded gray apple icon screen, and iTunes doesn't recognize it. I've tried pressing center button and menu but it doesn't do anything. Any help please???