The back light on the screen works, but only when the screen is almost closed (just before hitting the shut switch). When the screen is all the way opened the back light shuts off and the LCD can still be seen, but it is so dim, it is almost impossible to see. The back light works but only at an angle that makes it impossible to see the screen. Is this a boken ribbon cable? Is there a sensor that tells the screen when the screen is all the way up, and thus out of adjustment? This problem is not heat related, because it works all the time, but wrong.