Charging problem on IPAD3 after battery change

I've received an IPAD 3 that had an battery change and after that battery wont charge and goes into an reboot loop. So far i've managed to hook it up to charger, turn it off and get the battery charged but it takes forever, like a day and more... Strange thing is that i've tested with 3 batteries now and it's the same with all of them.

I've noticed that when connected to charger (wallcharger 12W) it might say 55% on IPAD, if i disconnct chargers it drops to 51%..

I've tried with another digitizer, another dockport/chargerport and nothing seems to solve the problem.

Anybody got a tip of what could be the problem here ???