I currently have the same problem, If the backlight turns off when you move the screen it could be the display cable or the actual backlight bulb. Mt computer has a bad backlight. I would have someone open it up and check and make sure the display cable ir all hooked in securely or just replace it. If its not the display cable then its just like mine. the backlight is an extremly hard process to replace. The easiest way to fix it is to just replace the whole LCD display. Sounds hard but its very pretty simple. LCD's are about 80$ on ebay.
Hope this helps!