iPod 4th gen thinks it is charging even if it's not

Hello, I have an iPod 4th gen, and it thinks it is being charged, all the time. It always displays "charging" icon and lights up its display all the time, and consequently gets drained quickly (when I really have to charge it). I have done all the basic steps, reset, reload firmware, restore. Still the same. What should I do, short of sending it back to Apple?