iPhone 4s not charging but syncing and showing charge icon.

So I replaced the cracked digitizer on my boss Iphone 4s. Everything went smoothly. I plugged it in put a final charge on it before I gave it back to her. When I picked it up, unplugged it, phone went black. So I plugged it back in. Starts up, but would shut off everything I unplugged it. Replaced battery. Stays on but will

Not charge. When I plug it in, the charge icon appears but the percentage goes down. When unplug it into the computer, it will sync but still nothing. I also replaced the charger port assembly and did a full software reset.