- See if placing the iPod in Recovery Mode will allow a restore.
- Next try DFU mode and restore.
How to put iPod touch / iPhone into DFU mode « Karthik's scribblings
- If not successful and you can't fully turn the iPod fully off, let the battery fully drain. After charging for an least an hour try the above again.
- If still not successful that indicates a hardware problem and an appointment at the Genius Bar of an Apple store is in order.