Then the power is not the cap, it could a power transistor or a Y-Board or anything else.
Bottom line I don't think that anyone here has enough knowledge to help you fix it.
The point is - paying anyone else to fix it - doesn't make sense - ether you figure it out yourself or just spend the money to get a new tv.
I faced same choice about a year ago when back then my old 6 year old 42" LG Plasma TV has failed
But the upside is - back then I paid almost $1700 for bottom line LG 42" 720p plasma, and a year ago I got a 55" 1080p Panasonic ST series plasma for $1000
Point is technology moves ahead - you could buy 42" 720p TV today for under $350