Does the computer have an external VGA connector? If it does, try to connect an external monitor to see if the system is really completing POST. Also see if you can see a very dim display by looking at the LCD from an angle after the computer boots. If you can see a dim display the backlight for the LCD is bad. If that is the case the LCD amy have to be replaced.
i took the monitor off and found the mmonitor connection. when i used another monitor it worked. i also switched the connection with the suspected bad monitor and got a picture, but when i put the monitor and computor back together i got no picture again. it still come on but not the monitor. unfortunatelly it is a combo computer with the power supply built into the monitor section with a plug in type distribution board that plugs in when both parts are connected.