Gather your spudger and key fob

Prepare a surface to work on (ensure it's won't damage the piano black exterior coating)

Using a small pry tool, gently press into the small indent near the front of the key fob while pressing up to pop off the battery cover.

Remove the coin-cell battery type CR2032 by prying upwards in the small recess

If all you want to do is replace the battery, stop here.

Using a stiff spudger or other prying tool, pry back the plastic tabs on the top and bottom of the plastic sides (circled in red)

Take your time here and go slowly so you don't break the clips

Next, pry up the middle shell section using the four tabs at the sides of the case. (outlined in green on the right side)

Last but not least, gently pull out the PCB from the top housing

The coin cell battery holding bracket (circled in orange) can be removed by gently grabbing with tweezers and lifting straight up

And just like that you're done!

A relatively simple teardown. Go forward and put that PCB to good use with a custom fob housing