0x80a40015

You will need to wait for the XBL service alert to pass. Xbox is aware of this issue and is working on a fix. In the meantime you can try and offline update or the update
troubleshooter. I'd also advise doing a powercycle of the console. https://support.xbox.com/en-US/xbox-live-status

Just wait, Xbox live core services are currently down and we all can do is wait until Xbox fixes it, you can check more details in the link below:

https://support.xbox.com/en-US/xbox-live-status

Good afternoon. Try unpluged the console and internet for two minutes and plug. Its resolve many of the situations.

Try performing the hard reset EXACTLY like this. Hold the power button on the console for 8 seconds or until the power shuts down completely. Unplug the power cord from the back of the console for 5 minutes. Plug the power cord back in and restart
the console.

We have the xbox set to offline mode because we do not have the internet. We are getting this code in offline mode.