What's wrong with my tv

I have a 42" Viore model PDP42V18HA 720p widescreen plasma HDTV - 16:9 1000 TV. I purchased it about 5 yrs. ago. After about 2 yrs. the picture went out with just a blue screen. I was told shut it off for about an hr. which I did and it worked again. This happened again about 3 months ago and I did the same again and it came back on. This week it has gone out again and will not come back on. I removed the back panel and tested for power after unpluging all leads for what I call the power board, there was power out put. It is the board top center with 5 heat sinks. I felt each one for heat. The top left heat sink gave a shock and was hot. What do you think is wrong?