Panel powers up but black screen no sound

Already got a new tv awhile ago, but figured I’d try to fix this to save from recycling

50PFL4756/F7 W

Back panel lights up but no image or sound from Roku OS

How can I confirm a bad panel before wasting time or money ordering replacement boards, I am decent at board work if applicable but I’m not a engineer so I have no idea how to sit down and multimeter test out a whole board or determine faults outside of obvious visual failure

The metal cover for the t board had some dust maybe soot from around those round mosfet lookin things, Maybe bad/fried t-con?