Here is What's Stated in Step-3 : (There is a small plastic tab that reinforces the front corner of the Xbox.) Actually, the "Tab" is NOT SMALL at all. See the Picture: The "TAB" is the Piece that this Person has their Thumb on, is the Tab that you NEED TO SLIDE TOWARDS THE "REAR" of the Unit. You will be able to tell How this Large Tab Holds the Top and the Bottom Case Covers together. Take Note how to Replace this tab back where it Belongs, when you are putting the Case Covers back together. Hope that this comment will help you. 6-29-2017