continually restarts to the "Smart TV powered by Tizen" boot(?) screen

I have a similar problem that I am unable to fix. I have a UN50TU8000F model that continually restarts to the "Smart TV powered by Tizen" boot(?) screen. I have done everything suggested up to a factory reset which seems to be the last resort suggestion from Samsung before assuming it needs service.

LED panel lights fine. I have a seemingly steady 13V at the output of the power supply board with no change on my multimeter during the restart. I am assuming the fault is on the processor board. Originally it would operate for ~5 minutes before rebooting. with the time between restarts gradually decreasing to about 30 seconds between reboots as it "warmed up". I assumed a warming component was responsible, but no obvious overheated components by thermal imaging on either power supply of main processor boards. Removed the processor heatsink and ran it expecting the more rapidly heating processor would shorten the cycle time. No change in time from cold start to reboot,

At a cold start I have also tried warming the processor board, or warming the power supply board to about 50 C with a heat gun with no apparent effect on the reboot "cycle time".

Short of blindly replacing the main processor board, I have been tempted to heat it in an attempt to re-flow any bad joints that may be responsible for the issue. A last resort, but at the moment I have little to lose.

I suppose the problem could be in software, but assume the factory reset should take care of anything like that??

If anyone has any other suggestions I would like to hear them.

At the moment I have no clue what is initiating the reboots, and have a less than three year old piece of electronic junk to dispose of.