Remove all of the screws from the bottom of the system, except the one covering the WiFi.  The WiFi cover is the only non-silver screw (not pictured).

 

 The covered screws at both ends of the laptop must also be removed.  At the back end the screws are covered with a small, circular white cover.  At the opposite end, the screws are covered by a angular black piece of padding.  Remove all four covers and their screws.