Orient the Xbox 360 S so that the hard drive port is facing up and the faceplate is facing to the left.

Insert a metal spudger between the black bottom vent and the silver rim of the bottom bezel, in the rear right corner of the vent.

Rotate the spudger away from the console, prying the vent up from the bottom bezel.

Be sure to rotate the spudger far enough so that the clips on the vent are lifted past the silver rim of the bottom bezel.