Xbox One S not showing up on TV

The xbox 360 e display isnt showing up on the tv, the 360's power button is just constantly flashing, and nothing is showing up, its just saying resolution mismatch change device's resolution..

I have everything set-up, the hdmi cables are in, one in the xbox, other in the tv, the powerbrick is working.. but nothing is showing up, just the same message.

Try this Troubleshoot blank screen solution or this System
updates solution.

If you get to the stage where it says "use offline system update", (OSU), and you are in the Insiders preview ring, make sure you unenroll from Insiders prior to attempting OSU

I have tested and confirmed that my cord and my TV port both work.

It sounds like you may have a faulty HDMI cord. Have you tested this by using a different cord?

Hi HamyMcBerger73,

I'd be happy to explain why this issue occurs and provide a solution that will hopefully resolve this startup problem. When you start the Xbox One console, you expect to see the green Xbox startup animation screen. During the startup animation, your console
runs a full system check on all hardware components, validating the firmware and the operating system. This is very similar to the way a PC starts. The startup animation screen can take several minutes before transitioning to the next screen. If the system
check fails to run the startup animation three times in a row, the console is flagged by the system as “do not run.” This will block the startup animation from running, and in its place you'll see a black screen.

In order to determine your troubleshooting steps, after pressing the Xbox button you'll need to leave your console on this black screen for at least 10 minutes.

Note: A black screen doesn’t always mean that there’s an error. The system checks described above run in the background and can take several minutes to complete. This may appear to be an error since you'll only see
a black screen, but it can be completely normal except for the absence of the green startup animation screen.

If you have waited over 10 minutes and the screen does not transition, try booting up the console in the following way:

• 
  
  1. If there's a disc in the Xbox One console, eject it.
  2. On the console, press and hold the Xbox button for 10 seconds to turn off the console. Unplug the power cord and wait 5 minutes.
  3. Re-connect the power cord. Press and hold the Xbox button and the
     Eject button until you hear a beep to turn on the console. You’ll hear one beep right away and a second beep 10 seconds later. The power light will flash on before the second beep. DO NOT LET GO until the second beep occurs.
     
     Note If you have an Xbox One S All-Digital Edition, you’ll need to press and hold the
     Xbox button and the Bind button instead, as your console does not have an
     Eject button.
     
     In either case, this will boot your console in low resolution mode (640 × 480). To reset this setting, press the
     Xbox button to open the guide. Go to System >
     Settings > Display & sound > Video output, and then select the resolution you want from the Display dropdown.
     

Please give this a try and then let us know if the console continues to experience this startup issue.