Microsoft support has the solutions. Hopefully
If you’re one of the “small number” of Xbox One players who are having difficult booting up after the new Xbox one Experience update rolls out today, don’t panic. Yet.
Microsoft has acknowledged issues with first boot, content installation, and accessory and accessibility issues after the update.
If your console gets stuck on the green Xbox One loading screen, you’re advised to just leave it alone for fifteen minutes. If it still doesn’t load after 15 minutes have passed, you need to hold down the power button for ten seconds, and wait for the machine to power down. Leave it at least 15 seconds, then turn it back on again.
Other problems include missing tiles (go toHome, highlightMy games & appsin the big tile, press theMenubutton on your controller, and selectQuit. Then relaunchMy games & apps), broken voice commands (youcan usually resolve this issue by rebooting the console), and repeated prompts to fill in your password (you’ll need to de- and then re-link your console).
You may also need to fiddle about un- and reinstalling games and apps if they’re problematic, and possibly change your default storage location.
For the full listof issues and solutions, click on this helpful link.