iPod won't turn on

My iPod had empty battery. I tried to charge it with wall charger (for the first time, till then I always charged it in computer), but it didn't charge, at least I think, because since then I can't turn it on. It's completely dead. If I plug it to my computer, itunes open, but then the iPod keeps lconnecting and disconnecting itself from computer and sentence "Preparing iPod for recovery" is showing. IPod isn't visible in iTunes. Does anybody have a clue what's wrong? Thank you for answers.