Once you have created a gap between the two halves of the bud, gently pry them apart with a plastic opening tool.

You may need to work your way around the entire earbud with the opening tool. Take your time and do your best not to deform the plastic.

Carefully remove the top half of the bud.

Be careful when pulling the halves apart! Sometimes the battery assembly gets caught in the case. If the top half of your case doesn't come out cleanly, skip this step and disconnect the cable in step 4 before separating the two halves of the bud.

During reassembly, line up the arrows on the two halves of the outer case, then press the halves together until they snap into place.