Hi,
With the camera on, try shining a torch (flashlight) at an angle close to the screen and check if you can see any images at all in the screen.
They will be very faint so trying in a darkened room may help to see them if they're there.
''If you can't see any images'' then there is either a motherboard problem or a screen problem
''If you can see images'' then there is a backlight problem. Either no power to the backlights from the motherboard or a faulty screen.
Looking at an image of the LCD I would guess that the 2 wires shown highlighted would be the backlight power wires.
Check that the flex cable connector ends are clean (gently wipe them with a Q-Tip moistened with Isopropyl Alcohol 99%+) in case there are any greasy residues on them from being handled etc and then carefully reinsert the cable into the connector on the motherboard and check.
[image|2704087]
(click on image to enlarge)