here is what it sounds like it might be:
Either the power supply has an issue , or you have a panel
A repairman will usually just ordered the boards and you will spend over $300 probably around $350
It could be just a few bad capacitors on the power supply, if you want to attempt the repair yourself you can do a visual of the power board caps will appear swollen on top.
look at the photo I am uploading to see what a bulging cap looks like
With the back removed you will see a few circuit boards the upper one (ac cord runs to it through a small board) is the power supply, it has alot of capacitors on it (cylindrical standing straight up soldered in and marked on the sides with the positive/negative sides and MF and Volts values)
Philips and Samsung use 2200Mfd or 3300mfd at 35Volts rating capacitors, they cost about $1-$2 each
usually I replace two of them (or all the bulged on top ones) .
The power board and back unscrew with a torx bit and screwdriver size 10 and 15 , if you do not know how to desolder and resolder then do not attempt this as you may damage the TV more than fix it.
We do not recommend do it yourself, but depending on your knowledge and technical ability you may be able to.
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