Why isn't my Playbook charging past 75?

2 month ago I buy PB from website. And I got some problem.
For about detail
1.) My PB fully charge only 75%
2.) I cant change brightness it also at 50%
3.) LED always on cant close its.

I search this problem from internet but can't find way to fix its. Have anyone in here have same problem or know how to fix please tell me. T^T



Sorry for my English HAHA

What is the history of the device? Is it used, refurbished, or new? Could it be suffering from some kind of physical issue like moisture damage or damage from a drop?