Blue Screen

About 10 months ago, my sister-in-law turned off my cable box instead of my tv. (hitachi 50V500) LCD rear projection. I have since had this blue patch which started in the upper top left of the screen. It now has successfully covered 95 percent of the screen. I can still see images, but the coloring of the tv is all wrong. Adjustments using the OSD controls have no effect. I feel that the screen itself is ruined and needs to be replaced. I have the tech manual for the tv, but it doesn't cover this problem. If anyone can help, I would be very grateful.