You may need the power supply board resoldered as I had the same problem. The guy listed below can do it for you as I shipped mine from Illinois to him in California... Piece of cake getting the board out of the back and it's not too fraigile... Just pack in bubble wrap and it will be fine. My TV is now working great.
BUT DON'T DELAY AS SOONER LATER TV WILL NOT RESTART..
How did you pay to have him resolder the power supply board. Last year we spent 450 repairing this same problem. And now exactly 1 year and 1 day later we are having the same issues with our tv. It shuts off and won't come on for a few hours.
Please help, trying to figure out if we should get it repaired or purchase another tv.