Use a Philips screwdriver to remove the two remaining screws from the grip.

Then, gently pry the mouse button cover from the grip using a flat-edge screwdriver. There is just enough space to get a fine driver wedged in place.

Use your fingernails or a spudger tool to push each plastic tab back (green)

Lastly, slide the button check clips down and then up in the direction indicated by the arrows to remove the button cover from the grip.