"This accessory may not be supported" no charging

I have an iPhone 6 plus a customer brought in. The camera would not hold focus and the phone will refuse charge. I changed the back camera and it was fine. The charger port I cleaned out but it kept displaying an "accessory not supported message so I changed that as well. Still had the same message, so I cleaned out the pins on the board and the new charger port. Still the same thing. Ive tried updating, restoring, putting on airplane mode, ie. It only charges when dead and when it turns on it refuses charge. As soon as I plug it in it charges for half a second then instantly displays " this accessory is not supported". My chargers are original Apple and I've tried 7-8 different chargers. Im not really convinced this is hardware but I'm open to answers. Any help please, Ive tried everything I could think of except downgrading IOS and jailbreaking, and using bypass with cydia. However I highly doubt my customer would like to jailbreak her phone. It doesn't look like its been fixed before from my observation.