Flip up the little tan tab on the connecter of the button pad's ribbon.

Don't use a metal object for this step. A fingernail will do. Simply slide your fingernail under the lip and lift slowly. You may need to lift in different areas along the tab to get it all the way up.

In the second image the top tab is open while the bottom is closed as an example of what the two positions look like.

The tab is reversed for the button pad, the tan part is the tab while the black is the connector