I don't have an answer but have the same problem that developed today. From what I read, it appears the IR sensor in the TV went bad. I can see a light in the TV flicker when I try to use the remote so I'm assuming the signal's getting to the TV but nobody's home.
I've pretty well decided to replace the POS since there's a blotch on the screen that I've lived with for a year or more after I contacted Samsung and they determined it would need service and it was out of warranty. I believe one of the LEDs went bad but not sure. It bothered me, but I was living with it until this came up.
My question, if you're still visiting this page, were you able to continue to turn the power source off and when you turned the power on, did it come back up? That's what I did this morning and it turned back on, but I'm afraid it won't stay locked on and I'll have a dead TV and I want it to last until the Super Bowl sales start which means at least a week or three.