Black screen after bootup on Thinkpad T40

[etherburn]

Has this every happen to anyone? When I boot up on my T40 laptop its just a black screen. I sent it back to a service center twice, when I get it back its fine and bootup the computers its fine. Then the next day its just a black screen after the bootup. I tried using the FN and F7 key but nothing.
I only see the Z symbol on the laptop is constantly lit.
does anyone know of a solution?

[EOMtp]

Turn the unit on in a relatively dark place (not totally dark) and look for very faint traces of what you think you should be seeing on the screen. If you see what you expect, then your LCD backlight is out, i.e., the LCD panel and/or the inverter may need to be replaced.

It may be also that the small button which turns off the screen when one closes the lid -- the small button at the top left of the unit, lined up with the F2 key -- is stuck in a depressed or partially depressed position. Make sure it moves in/out freely. You should be able to feel the light spring action if you depress the button with your forefinger. Do it while the unit is on and see if that activates the display.

[etherburn]

that didn't work, tried the dark room while turning on the screen. Its still black and tried the spring action button on top of the F2 button. Its not stuck and I pushed it while the laptop is on. Its still a black screen with no picture.