Dell XPS 15 L502x - Randomly shutting down, and not performing simple

My Dell XPS L502 is shutting down randomly, firstly i thought it was a windows issue as i have upgraded to Windows 10, then while reverting it back to Windows 7 and after removing the windows from laptop i cant reinstall it, as during the boot-loading the laptop is unexpectedly shutting down. it might be the adapter, but im using the original adapter, batter is down so it is used as a desktop, meaning its always connected to a power adapter when in use; i did opened it and closed the laptop and might have in the process damaged some screws as i am getting a light shock when touching the device.

Please help me.