The button is very difficult to replace by disassembly. The seller recommends to pull out the button slightly with your fingers and slide a screwdriver around the seam. I found this didnt work for me

The old button is clipped around the housing with three clips. Cutting the centre of the button out allows easier access to the clips from the inside

Be careful with the cutters to not go too deep and damage the inner circuitry of the button, try to cut parallel to the front of the button

The green ring represents the remains of the old button and the red ring represents the button housing which the button is clipped to