The sound still comes on so I wouldn't think the entire power board is bad.
It's not. The circuit with the inverter is faulty. Repairing these multi-layer boards with the components compacted into a small footprint is difficult - even for a seasoned technician. That repair is as much as simply installing a new board in most cases.
Samsung advises replacing, rather than repairing, entire boards.If you open up the set, and can get the board number, I may be able to help you locate a new one.