Question Samsung UN75RU7100 on and off every 5 seconds

[Rsreid]

I bought this tv hoping it had a bad power board or main board. I replaced both. It still power cycles. My next option is always LEDs. I just finished replacing the LEDs and it’s still power cycling. Any suggestions? I’ve never really used a multimeter but I have one. Im an IT guy that’s used to swapping boards, and it’s worked 99% of the time for me so far with tv repair. What else can I try?

 

[Rsreid]

Now it seems to be on, dim, off for twenty seconds then starts over.