Backlight problem

My first Macbook started having a similar problem about 2 years ago (putting it at 4 years old as well) where moving the screen would cause the backlight to flicker. Eventually, the backlight went out all together. My final diagnosis was that the point on the logic board where the backlight inverter connects was bad - only hope for repairing it would be to either risk resoldering it or buying a new logic board.

However, the issue could lie in the inverter board itself being bad, or even the screen - both of which are much cheaper to fix. So don't give up all hope! If you have any repair experience, you could try diagnosing the problem yourself, otherwise I would tell your friend to just take it to your nearest Apple repair shop or store and see what they say.