either learn to troubleshoot electronics with a multimeter, scope, etc, take it to a TV repair place or trash it and buy a new one.
A lot of times modern TV's have kinda crappy power supplies or motherboards and they die. The parts are expensive, labour is even more expensive and you may get more crappy parts that die in a year.
Your TV is like 7 years old, it's probably toast and the cost to even find parts for such an old TV isn't going to be worth it.