I'm not a hardware expert and I don't think anyone here is either. However, if it was the battery, I think that you would see other signs of battery problems such as inconsistent charging, the device not holding a charge, and things like that. Maybe it's a short, but I would have no way of knowing that either. Why don't you contact iPad repair support and explain it to them.
https://www.apple.com/support/ipad/repair/
If this was my iPad, I would make an appointment at an Apple Store and ask them to take a look at the iPad. It is much easier to book a Genius Bar appointment if you use the Apple Store app.
https://itunes.apple.com/us/app/apple-store/id375380948?mt=8