iPad Air wont charge properly, battery acting strange.

I’ve been in the repair business for about 2 years now and a problem i have encountered from times to times when doing some sort of repair on the iPad Air is that the iPad wont charge or the battery starts to act out, e.g booting up with 1% batterylife and jumps to a new percent number when putting the charger in.

The thing is this problem usually solves itself when i disconnect and reconnect the LCD and digitizer, but what is it that causes this in the first place?

Just have to point out that i am using a pick to disconnect the battery before starting to disconnect things from the motherboard.

LCD, Touch and Homebutton works fine even when the battery acts out or ipad wont charge so i would say everything is connected properly when this problem occurs.

This just happened today when doing a glass replacement, and to be honest it gets quite stressful when something doesn’t work properly and you dont find a logical reason as to why the product acts the way it does. But as i said earlier the iPad works great now after just “redoing” the repair by disconnecting everything and connecting it again. Still dont know why the iPad wasn’t working properly the first time i reassembled it though.

So if any of you know what’s causing this problem i would love to hear it.

Thanks!