Before totalling it, it may be worthwhile to get a replacement inverter to see if that is the issue. Inverters are usually cheap and it sounds like it very well could be the issue.
If he is getting a backlight, it's not the inverter. A bad inverter would give a black screen. If he is getting a solid white screen, he is getting a backlight, but no picture. If the LCD works on another computer, and you've replaced the LCD cable, then you could have damaged the LVDS transmitter on the motherboard.