Unable to unmute the microphone

It is a brand new headset and works on my laptop.

I saw this for the first time today and only a FULL Shutdown and remove console power cable resolved it for me.

Try Settings>Power and startup> Turn off>Full shutdown.

It is a brand new headset and works on my laptop.

See my comment above. Thought I was replying to OP.

You normally see that Icon when a headset is not detected for the logged in account. It could be an issues with either the headset or the controller. If you have a different headset or controller try swapping things around to see if that helps resolve the
issue

Hey Lenner

Thank you so much for taking the time to post this on the Xbox Forums.

This depends on the type of the headset you are using. You can take a look at
this article and see if any troubleshooting techniques work for you.

Alternatively, again, depending on what you are using, you may have to manage your audio settings by selecting Audio on the guide.

You can follow these steps to find this:

1. Press the Xbox button on your controller.
2. Scroll over to the right till you see the gear or cog icon, it will read
   System.

• If you have a compatible earphone piece or headset, you will display Audio
  in between Settings & Xbox Assist.

You will see three options here:

• Headset mic will allow you to manage how loud the audio output will be
• Headset chat mixer will allow you to balance the game and party chat
• Mic monitoring will allow you to adjust how sensitive the mic will be towards you voice.