Turn on the Xbox 360
Press the Guide button on the controller
Go to Settings
Select System Settings
Select Console Settings
Select System Info
Note the console serial number if needed
Go back to System Settings
Select Storage
Highlight the Hard Drive or Memory Unit
Press Y
Select Format
Confirm the format
Go back to System Settings
Select Console Settings
Select Initial Setup
Follow the on-screen prompts to complete setup
If needed, remove any connected USB drives or memory cards before resetting
If needed, perform a manual reset by holding the power button for 10 seconds and restarting the console