A friend's 6g Ipod nano would not wake from sleep. The rocker button seems to be stuck in the 'off' position. Naturally it was just after the warranty had expired. Nice one, Apple!
I am not a tech, just always curious. I managed to get the front screen off OK with the special ifixit tool and removed enough inside to get to the button but the darned thing is so tiny that even with a magnifying glass, its just too small to see what is going on, the rocker part of the switch being possibly 1mm wide if that. I think the rocker part is malfunctioning and has shifted somehow. I poked it gently with the spudger to the 'on' position so at least it wakes up now when you plug the usb charger in and put it all back together OK,
Unless you have serious magnification available, don't bother with trying to fix this problem. These things are so tiny inside that its amazing and no surprise that they malfunction. I don't know why Apple didn't make it wake from sleep with a screen touch or when you plug the earphone in. I suggested to my friend that he get it fixed professionally. Well at least I tried.