This Macbook has no backlight due to a common F’up – pin 1 of the LCD cable is bent. Pin 1 is for the LCD backlight. The board’s current sensing circuit on backlight output will notice that pin 1 is touching the connector housing itself, shorted to ground, and not send power through to the circuit. Bending the pin back fixed the problem.

At Apple, this issue would have cost the customer $1200. You might not believe me, which is why we have it all on tape. :)