Had the same problem with Samsung 55 inch. The the digital audio (optical) connector flashes intermittently as it clicks. Took it to a tv repair guy. He said he had the tv on for 3 hours and nothing happened. He said that if the TV turns on it may not be the power board. But the board where everything (inputs and outputs) connects. But said he could not find parts (probably because he did not know what was broken). Any of the boards cost $250 or more. Cost $30 for that advice. I took the TV home and it worked for more than 5 hours before the clicking started. Every time I had taken the TV apart it will work for a few hours so maybe it is a heat issue or electricity dissipation fixes the issue. I called a Samsung authorised service agent here in Melbourne. Asked for $160 for a home visit or $88 for me to bring it in. Without any guarantees it would be fixed. Anyway - don’t ever buy Samsung is the lesson I have learned.