Inspired in the [guide|75780|guide for the Anywhere MX mouse|new_window=true], I opened the Anywhere MX 3, and although it's not built the same way, the solution was simple.
After carefully removing the 4 pads in the bottom of the mouse, then the 4 screws below them, I opened the mouse and saw the white elongated button responsible for the click.
[image|3276464]
I cut 3 small squares of black electrical tape
[image|3276466]
to fit the contact point with the click button on the other side, on the top of the mouse. I pasted the 3 squares one on top of the other in the place indicated by the screwdriver:
[image|3276465]
then just reassembled the mouse cover, screws, and pads.
This fixed the problem and now my mouse works as good as new :)