Hi, start with measuring the HT transistor (BU2508DF) for shortcut, if so: this is likely caused by bad solderings at the capacitors (connected to the C of the HT transistor) C101 / C102.
Of course i assume you're confident enough with electronics to work inside the tv yourself.
It's usually a small repair with these tv sets, unfortunately the value of a working one is the price of a good pizza so paying a repairguy might not be worth it....
Cheers..