I can't use the serial port on the laptop to even view the screen on my desktop PC as the connections are different. The power cable feeds the monitor without the use of the serial cable.
Ok, two things here : It sounds, from that, like he is trying to plug the monitor connection into his RS232 serial connection. Does he have a monitor connection on the notebook at all?? Check for that first.
Also, try booting in safe mode. I have a feeling he will get full colour and brightness back. Why?....
I've worked on many many notebooks with this problem. Its a total pain in the @$$, but it is usually related to a driver issue (hence it working in safe mode). Uninstalling the graphics driver, and LCD driver (if you have one) then reinstalling can do the business....
I don't fully understand WHY it dims, but I've always managed to get it back. I suppose it IS possible that the backlight has gone, but again -- if safe mode works, then the screen should be fine!
Make sure you have your insurance sorted just in case!!