With the screws removed, we can try to remove the palmrest.

Removing this part may require quite a bit of force as it's held by two clips at both sides of the mouse. Take your time and don't rush this process.

If you remove the pinkie rest piece you should be able to see a divide between the upper palm rest and the rest of the shell, we will only be removing the upper part for now.

Try to carefully pry it open using a spudger, creditcard, wiggle the tool and take your time and slowly increase the amount of force exterted while wiggling.

Once one side's clip has popped out, slide a credit card/pick all the way along the newly created opening to the other side and wiggle the other side's clip loose as well (this shouldn't take nearly the amount of force used for the other side.)