Several owners of the latest generation Apple TV are complaining that the set-top box is randomly waking up itself and/or connected TVs.
The issue was first posted on Apple’s support forums and confirmed to be true by AppleInsider. Affected users may see their Apple TV turn back on as quickly as a minute after shutdown.
TV sets with HDMI-CEC support will turn back on if the Apple TV is powered on. This would be a waste of electricity and could potentially cause a disruption of sleep. For those who still have plasma TVs, burn-in is still a risk because tvOS may not run the screensaver.
The exact cause of the problem is still unknown, however several users are blaming Bluetooth or AirPlay. Some users have fixed the issue by closing most (or all) apps before putting their Apple TV to sleep. If you are concerned with keeping your TV off, you can easily disable HDMI-CEC in tvOS settings.
The solution to the issue will most likely be a software patch that is rolled out to users in the coming days or weeks.