Why won't iPhone 6 take a charge after water damage?

Hello. I had a customer come in a couple of days ago with a water damaged iPhone 6 that would not turn on. After opening up the phone, all moisture appeared to be gone because the customer had placed the phone in a bag of rice. After doing some tests to see what the power source problem was, I found a new battery got the phone to turn on. However when the phone died, the customer tried plugging it in to recharge and noticed that it wouldn't charge.

When the customer came back in, I tried a couple of different things to see what the problem was again. I tried a different battery to see if it would come on, and it did. However when I had it on this time, I tried to plug it in and the charging port wouldn't work. So I tried a couple of different charging ports and none of them would show the phone charging.

Any suggestions to try and fix this problem? I'm assuming something got wet on the motherboard that wont let the phone take a charge. I also had the customer restore the phone and to reinstall new software. Didn't work.