Display stops working when unplugged from charger

My 80 gig Ipod stopped working and is not under warranty. I replaced the battery, did nothing, and then replaced the logic board and started working again. As soon I unplug from charger, the screen goes blank. Plug back in, and the sceen lights up again. While plugged in, click wheel works and can scroll through menus.

I must mention, on one of the last reassembly steps when reattaching the headphone jack ribbon, the clasp that flips down to hold the ribbon in place broke off, so the ribbon is being held in place with electrical tape. Very aggrevated about that. Not sure if this contributing to the problem. Of course, when I plug in headphones when the Ipod is plugged into the charger while it's working, there's no sound.