iPad 4th Gen battery percentage does not work/go down

So I have an iPad 4th gen (retina, 16g, wi-fi) and I've had some problems with it, here the link to that: Ipad 4th Gen not working at all

After I restored my iPad through iTunes it started working as normal but the battery was at 30% and after 20 mins the screen just went black and it didnt have any low battery signs. I left it on charge for like the whole night and it showed 100% in the morning so i unplugged it and after using it for 40 mins the batter percent was still at 100% which was strange. So i put it on charge for some time and started using it and after 40 mins of use (watching youtube) it got really warm and the screen went black and if i hold the Power/Sleep and Home buttons it doesn't show anything even after being on charge for over an hour not even the battery symbol, the screen is just black. So basically what happens it charges up to "100%" and after 30-40 mins of use it get hot and blacks out on me. Its so annoying.

Any ideas?? Also when i got the ipad about 2 years ago when i used it i kept on getting warm all the time when i was using it. Any answers would be helpful 🙂.