Ipod classic disconnects/turns off whenever it's plugged in

My Ipod classic disconnects/turns off whenever it's plugged in. I've had USB sticks in the slots and they work fine. I recently brought new charger cable so that's not the problem. I can turn it on and it works fine (although can't get anything put on there), but the second I plug it in the ipod itself shuts down or freezes and I get a message saying it's been disconnected