Backlight on Qosmio G35 is off

[797ckenj58]

I instaled Vista on Qosmio G35 laptop. When instalation was in half, backlight went off and now I can not turn it on. I instaled original Windows XP from Qosmio restore DVDs, but still it is off. I checked screen, inventer and LCD cable with other laptop and it is working.
Please help.

 

[frozenlead]

Try outputting the signal to an external monitor.