Charging Problem - not charging

Hi

I have an ipad mini 2 - model A1489 - when plugged in on charge it shows the lightning indicator, showing it is charging, but never gets past 2% and will switch off straight away when its disconnected, which indicates its not holding charge either.

I've opened it to inspect it, looked at the circuit board under a microscope and can't see anything missing. This is, by the way, the first time its been opened.

Here's the fun part, its been used by a child so is likely to have been dropped, although no visible signs of damage or water damage. whilst on charge it reboots every 5-10 minutes too.

Could this be a worn a battery?

I've tried several different cables and I am using a good charger.