fast discharging of the batterie

Hey there,

I got a used IPhone 5S from a friend. He gave it away because it discharges completely in under 2 hours. While the phone is on without any process it is also really hot.

I read that a reset to default setup may help. But it is the same after it in the clean start enviroment.

Is it really the battery by themselves or is there any component that could have a short circuit or something like that?

Thanks a lot for your help.

Anton

After changing the batterie the behaviour is the same. Is there any possiblity to identify the component witch is the reasen for fast discharging?

Battery I bought:

http://www.amazon.de/gp/product/B00LZNS0...