Screen is randomly dimming and brightening and has never done this before

Mine is having the same issue; the screen randomly dims after a few minutes of watching normal TV. I constantly have to pick up the controller and hit the home button to brighten the screen then "A" to get back to the show. It just started and it's very
irritating.

The console does not come back on. The light on the console when I turn it off does the following: brightens, dims off, brightens, dims off, brightens, and finally turns off ( doesn't dim). The t.v turns off when the light comes back on the first time and
then turns back on after the second time it comes on. I have done both of your suggestions and neither worked.

Same exact issue. Never had this issue before. Did notice that when it switched episodes, it brightened back up, but then goes back to dim shortly after. Tried hard reset and unplugging it and did not fix it.

My Xbox One dimmed the screen last night, and then turned itself off after an hour of being dimmed. I had it sitting on the Ryse pause menu, and was out of the room. I don't think the screen dims while you're in sight of the Kinect, because I noticed if
I left the room for 15-20 minutes and walked back in, the screen would brighten back up.

I had this problem as well, and found a relatively easy solution, but can't promise it will work. All I did was turn on the Xbox (Then off and back on again to get the screen bright), and then let the Xbox sit until the controller turned itself off, and
the screen dimmed. Once you turn the controller back on, it will brighten once again, and from then on, I had no issues with the screen remaining dim when I turned the Xbox on.