Instructions
Turn the Xbox 360 console on, allow it to boot to the main menu screen, and then turn it off again.
Locate the hard drive add-on, situated on the top of the console. You will also see a release button located just in front of the hard drive.
Press the release button and lift the hard drive off of the top of the console.
Clean any dust or build up on the hard drive bay. This may cause connection or heating issues.
Position the hard drive add-on above the hard drive bay and lower it back into place. The hard drive will click once it is properly connected.
Turn on the Xbox 360 console and launch the "My Xbox" from the menu.
Navigate to "System Settings," and then "Memory." If the hard drive is working properly, you will see it listed as a memory component on your Xbox 360.