Xbox not connecting to HDMI and will not turn off

Update the power down did mot fix my issue

I have my Xbox connected via HDMI AND I have the standard AV connector connected to my Xbox at the same time (for Audio to turtlebeach headset)

If I turn off the TV and turn it back on, the XBOX will restart.. why?

Because the Xbox will switch to displaying via AV if the HDMI source is turned off, this calls for a restart.

Apparently this is what its meant to do Is ther a way of stopping this! as

Check that your TV is set to the correct input signal (HDMI). Check that the HDMI cable connection to your console is secure. Check that the HDMI cable connection to your TV is secure. Power cycle your Xbox One: Press and hold the Xbox button for 10 seconds to turn off the console, and then turn it on again. Also, make sure both HDMI ports are clean.

On some HD TV's there is a feature that, when connected to a device with HDMI, will "communicate" with that device. An Example of this is like my setup. I have a Blu-ray player connected via HDMI. When both TV and Blu-ray player are off, and I only turn
on the Blu-ray Player, they both turn on. It works the same way vice versa when I turn off my TV. I would go into your TV settings and look for a setting about HDMI "communication" and turn it off. Your TV might be telling your Xbox to "Turn on" and the Xbox
takes that as a command and "Turn itself back on" by restarting.

Hope this helps...

"Hdmi cord shuts system off when plugged in "

"A month later my other xbox does the same thing plug the hdmi in and shuts off"

The console should be completely powered off when setting up or connecting the HDMI cable.

Once physical setup is complete, Turn on the TV, AVR if using, then turn on console last of all.