MiPad smoking hot after laying on bed. Battery is bugging?

May 15, 2014
Recently, i bought a MiPad white version 64 gb!!

All works just fine until yesterday. I came back from work (10 hours away) and found my MiPad smoking hot on my bed. I think there was a problem with it going into standby mode (even then, i should be able to use a tablet for 10 hours straight right?) and i panicked a little bit. The screen didn't react anymore and thus i did a hard reset which seemed to work. The battery was 17% (when i went it was around 80%), which proved my hypothesis that somewhere it went out of standby mode OR it didn't fully went into standby mode in the first place.

I shut the apparatus off and let it cool down a bit. Charging the tablet seemed to work so i did that too. When the tablet was fully cool i turned it on again and .. all seemed to work well!! What a great quality this tablet is!
There is just a tiny problem and i hope you can help me with it. I noticed that the battery doesn't fully charge anymore. It says fully charged at 91% ? Is this a miscalibration of the system itself or can it be that due to the heat the battery is broken? What can i do to fix this (my first plan is to let the battery run down to 0% and then let it fully charge again but according to some doing just that is bad for the battery)? Any help would be nice :)