Instructions
Find the console serial number on the Xbox. This is necessary to provide when sending your broken Xbox to Microsoft for repairs. Look at the back of the console and just above the A/V (audio/video) port. You will see the serial number code aligned beside a bar code.
Find the Xbox's console serial number as well as the console ID, by navigating to the Xbox Dashboard. Power on the console and select the "My Xbox" option from the menu using your Xbox controller.
Choose "System Settings" from the menu.
Select "Console Settings" within the System Settings menu.
Choose "System Info" and copy down the console serial number and console ID codes displayed. These may both need to be provided when shipping your Xbox for repairs.
Find the console serial number via this alternative method if you cannot power on the console. Check behind the oval USB door. Disconnect any USB plugs from the USB door.
Push the USB door open to see the console serial number.