Follow each step carefully.
Press and hold the power button until the power off slider appears. Slide to power off.
Use a Pentalobe screwdriver to remove the screws securing the back cover. Carefully lift the cover off.
Identify the battery adhesive tabs attached to the battery.
Gently pull the adhesive tabs straight out to avoid tearing them.
Check that all adhesive residue is removed from the battery and enclosure.