How do you fix a phone that is turning on and off by itself?

Well I had the same problem as yourself, every time the back got hit it would turn off automaticly, so I decided to switch batteries from my phone, and when I had the second battery in and did a test run on the disturbance of the back, it didn't turn off, so my suggestion is to you check the battery in your phone and flick the backside of it and see if it turns off, and if it does see about getting another battery for sometimes batteries have an attendencyy to die on ya, hope this helps.