There is no fix for this problem, unless you check the power supply capacitors, in tv, there is small black button , which you push to turn ON and OFF, the tv, I am sure that switch is bad. Samsung not giving any fix may be issue with product liability.
my tv was turning off and on randomly. We turned off the "anynet" and turned off the auto shutdown in the menu under smart hub or systems. (He is grouchy now and pretending to be tired and cannot remember for sure) but I hope this will help someone. Tv is working fine now.
The tv turns off every 20-25 mins