ipad wont charge even after replacing charging port

Ok so a customer brought in a iPad 4th Generation with a broken charging port. The story was the lightening cable broke off in the port and the customer dug it out using a pick or something and the port was destroyed. I have put 4 different charging ports in it and they all do the same thing, when you plug the cable in the iPad will turn on but wont show its charging at all, no lighting bolt through battery, Ive also tried powering it off to see if it would charge while off and still wont. I am using the OEM Apple iPad charger and lightening cable. not sure what else could be going on.