Remove battery cover by sliding it off.

Unscrew the Phillips #1 screw in the battery compartment after removing the battery.

There is no need to remove its rubber feet since it is held together by only one screw.

Wiggle the grey part of the top to remove it by pulling it towards you(away from the scroll wheel).

Do not pull the grey cover towards the top and do not pull the part near the keys.

Reasoning by Jacob Hickey "because in the internal top part of the mouse where the buttons/scroll wheel is, there’s hinges-like “tooth” that’ll snap if you do pull on it. It’s like opening a jewelry box that has a hinge on one end of the box… if that makes sense…"

The image is what your mouse should look like in the end.

Push back small black clips to release the circuit board.

Slide up the metal battery connectors to free them from the casing. (Note that these are soldered to the circuit board.)

Fully remove the circuit board with the battery connectors and image sensor still attached.

Working from back to front (left to right in the first image) unclip the first two pairs of black plastic clips.

Slide the black upper casing forwards over the mouse wheel whilst applying pressure the two front clips to release them.

Separate the two casing layers fully.