Computer screen horizontal lines

[Mikey8888]

Attached is two images, my friend that gave me the screen to fix said that this happened while it was turned on and he was doing something else. Any ideas on how to fix this before i start blindly trying to find the solution. 

 

If you want more information then tell me what you want and ill try get it. 

 

The problem occurs when turning the screen on, though the white lines are less prominent. 

My plan now is top open it and see if there is any visible signs of damage / check ribbon cable continuity.