Use a small 2 or 3mm screw driver to take out the five screws at the bottom.

Keep the screws in a safe place!

The top and bottom shells of the mouse should open up fairly easily. If not, poke a spludger or guitar pick or even just your fingernail into the split between the shiny and matte plastic and the shell should pop right off.

When the top shell comes apart, be careful not to pull too hard as there is a connection wire that connects the side buttons to the upper PCB!