There are three ways to obtain the Xbox 360 motherboard's serial number from your console, including checking the console itself. The 12-digit number is necessary if you want to register your console with Microsoft. It is also one of the first pieces of information they will ask for if you want your console repaired.
Instructions
System Settings
1. Turn on your Xbox 360 console and go to the "My Xbox" menu.
2. Scroll to the "Console Settings" option and select it.
3. Open the "System Info" screen from this menu and the motherboard serial number will be displayed.
Back of the Console
4. Remove any disc that is in the Xbox 360 and turn the console off. Look at the back of the console.
5. Pinch either end of the wireless network adapter (if you have one connected) and pull it away from the system.
6. Locate the sticker above the A/V port and find the 12-digit motherboard serial number on it.
Behind the USB Door
7. Turn off the Xbox 360 and remove all USB devices connected to the front USB ports.
8. Push the USB door open and look for a sticker mounted above the two USB ports.
9. Take note of the 12-digit number. This is the motherboard serial number.
Tags: motherboard serial, motherboard serial number, serial number, your console, 12-digit number