Why does my Xbox One turn on randomly (and how do I make it stop)?
Solution 1:
I have had this happen to me many times now, I think it may have started when I connected some external HDDs to my Xbox for additional storage. Although that is just a theory that the HDDs might have something to do with it. My Xbox is also set to be fully turned off and no background updates.
My solution is simple yet very effective, buy a power / surge protector bar that has a switch which can turn the whole power bar on and off, ideally you want to have a power bar that has lights to indicate if it is on or off.
Next plug your Xbox in to that power bar which is dedicated to the use of your Xbox, last but not least turn the power bar on when you want to play your Xbox games, then shutdown your Xbox via the software interface when you are done playing your games and when the Xbox is fully off, turn off the power bar to kill all power to the Xbox, that way it cannot power on since the power bar will give no power to the Xbox.
Solution 2:
Is there something near the power button? Since the console doesn't have a physical power button, certain things falling/resting in front of the button may trigger it.
Additionally, is anything hitting the power button on one of the controllers? The controllers powering on can power on the console which they are synced to.
If this persists, I'd contact Microsoft as you may have some sort of a connection problem with the power button.