iPad does not charge, despite being plugged in

Hey,

Just last night I replaced the rear casing, battery and digitiser of my iPad 4th gen. The moment I booted it up, the battery was at 26% and everything worked perfectly. I plugged it in to charge, and it dropped to 20. I left it on charge for a while, came back and found no change. I unplugged it and came back in the morning.

The morning comes and I plugged it in again. This time I added a USB multimeter in too and watched the amp draw. Here's what I found.

When the screen is on full brightness and active, it pulls 1.8amps.

When the screen is on lowest brightness and active, it pulls .4 amps. 400mA

The moment I turn the screen off (lock it) wherever the brightness is, it drops to 0.00 amps.

After trying for an hour and ten minutes, it's only taken on 446mAh, and has gone from 20 to 7% (using it to type this)

During the repair I found nothing out of the ordinary. To get the old battery out, the board that connects the three cells did break, so it came out in three pieces. I didn't worry about it though, because the battery was the last thing in the case, the logic board was removed and I was replacing the battery anyway.

Is it a problem with the charging connector, the logic board or even this new battery I've installed? What do you guys think?

Just to recap, it's an iPad 4th gen Wifi. 16gb.