To change the batteries of the Kwikset 888 smart deadbolt you'll need 4 AA batteries (no tools required).

1) Slide black plastic case upwards on the interior side of the lock

2) Pull out battery pack from top of the electronics casing

3) Replace batteries

4) Re-insert into top of electronics casing with arrow pointing towards door

5) Slide black cover back in place

This video shows you how to do it: https://youtu.be/tW5qh08i36c