Ok, sounds like you have a display issue off hand. Try connecting an external display and see if it gets a picture. Also you can shine a flashlight on the screen, if you get a faint picture it's the backlight.
You also want to try resetting the smc. To do that you remove all peripherals, the battery and the power adapter. Then hold the power button down for a min of 5 seconds.
If the smc reset works you should be good if not there is a good chance you need to repair the computer.
Xen