Cube orange led goes off

Hello, I am using cube orange it was working very well until last night. Since the last night it connect pc hardly and when it connects orange led light goes off after connection but i can get datas.( last night one of the cell off my battery was 2.1V when others around 3.2 but we fixed it.) What is the problem on cube orange.

I always have the CUBE orange lights go off which indicates there is no power even though the battery was connected to the system. I understood later that dc spark on battery connection somehow corrupts the pixhawk power brick module . You need to slowly insert the xt plug into its socket .
It is a shame we have an expensive cube with a lousy switch connector in place !!