What is the problem

What error message do you get?

Please help me understand. What are you trying to register for?

Hi. My name is Brilliant, an independent advisor, happy to assist you today. Do you currently have any Xbox account?

Yes I do

Hi, Lukács. My name is Ron, I'm an independent advisor. I will be more than happy to help you.

Please do the steps below in sequence to do a factory reset and let me know if it works:

- Unplug the network cable if you're using a wired network connection.

- Power off your console, and then unplug the power cord to ensure that the console is completely powered off.

- Wait 30 seconds.

- Plug the power cord back in.

- Press and hold the BIND button (the one you use to sync controllers) and the EJECT button, and then press the Xbox button on the console.

- Continue holding the BIND and EJECT buttons for 10-15 seconds.

- Listen for two “power-up” tones a couple of seconds apart.

Note: If you don't hear two power-up tones after 15 seconds, it means this failed. Likewise, if you hear any “power-down” chirps, that also means this failed.

- You can release the BIND and EJECT buttons after the second power-up tone.

- The console should start and show the Troubleshooting screen

- Choose "reset this Xbox" and there you have an option to Keep Games and Apps (already downloaded) or to Remove Everything

Might be worth a shot,
clear cache and try again.