iPhone 6s+ touch lag on battery, but not when charging after screen an
I replaced a screen and battery on a 6s+. The customer brought it back afterwards because he said it was laggy. I did a factory reset on it but that didn't work. So I tested the phone with a couple other new screens but that didn't fix it. I also tried a couple new batteries but that didn't fix it. I noticed it was fine when charging but not when unplugged. Any thoughts on what might cause this?