LCD problem, but what is the solution?

I bought an imac off of ebay, the seller, who was not the user sold it for spare parts and claimed the motherboard was shot. When i tried it i got the chimes and then white screen, i did all the usual stuff, but with no luck, it would not go pass the white screen. after a bit of research i thought it might be the LCD and as i have another imac identical i made the switch and hey presto it works! the screen is the problem, but what is wrong with the screen, is it fixable. what can go wrong, it white, so i guess the back-lights are working, could it be a wire, is it worth the trouble or should i buy a replacement screen?

any help would be appreciated.