I work at best buy... um they will try and turn on the iPod....ask you whats wrong with it, put a big sticker on it and return it to apple. Now if apple happens to notice and tells best buy, best buy will probably contact you and make you pay for a new one.
BUT chances are they will never find out because im sure apple just uses returned ipods for parts.
if worst comes to worst...undo the jailbreak before returning it and they wont know