Started From The Bottom

The bottom of your button will have four little rubber feet. These feet conceal four screws. 

Start by carefully prying up the rubber feet. These are easy to misplace, as they are simultaneously round, bouncy and sticky. Which means they have three means of escape. Stick them right back to the bottom of the button somewhere. That way, they'll still act as feet, and you won't lose them. As easily.

If your button has a little red side button, this round red cap is not attached to anything. Once the button is open it will fall out and it will disappear forever. Prevent this fate by sticking some tape over this side button before you open anything.

Now, take out the screws. You're gonna lose some of these, It's just a given. 

Separate the bottom from the rest of the button. You did it! 

The upside-down button top makes for a swell place to keep any screws you've managed to not already lose. 

But Wait There's More

Reassembly

Putting it back together is simple but I do have some pointers.

For buttons with the red side switch, I move the tape holding the cap from the outside to the inside. It doesn't affect the button's operation and keeps the cap in place.

The actual top button dome slots into the sidewall with two easy-to-miss notches, so you'll want to rotate it until is falls into place.

Finally, I've found that the button really only needs two screws to hold everything together.