OK, this is not a PC tip, but whatever... Might help someone. A friend's iPod Nano 4th generation (A1258) went "dead". The thing didn't power on anymore and the screen was just blank. This happened after the Mac it was connected to ran out of battery juice.
The solution I found in the iPod Nano 4th gen. manual was simple: you have to reset the Nano. To do this, switch the hold switch (on top of the Nano) on and off and then quickly press menu and center buttons together and hold them for some 6 seconds.
This resets the Nano and it should run again fine!