Let's start on the Braille display first. The Bottom cover is held on by 3 M3x7 screws on the back edge, and two more M3 screws on the front (missing from our unit)

Finish releasing the top cover by insert a flat head screwdriver into the rectangular holes along the front and releasing the clips.

When the top cover is removed the scroll wheels will be free to move about. Note the orientation for reinstallation.