Just purchased a 65" 8 Series and love the picture, but when we turn it off with the Samsung remote, it turns itself back on a few seconds later. Turning it off again and it stays off.
I've read a few other threads about a router being at fault for random on/off, that's not the situation here I'm certain. I've disconnected from the network and it still happens.
Have you attempted testing if the TV cuts on while it is disconnected from the Apple TV? Also, what is the firmware version your TV is running?