How do I replace batteries of CareActive watches?

(1) PDF instruction: https://docs.google.com/document/d/1V88lJNgjr-oV4uJV6l2E_-DNKEiarp9qC180BTvl9aU/edit

(2) Video instruction: https://drive.google.com/file/d/1oR5WjGO-UdceuWQdZMFDQGsR-vW9ImXQ/view?usp=sharing