a) Parent unit

1) Unscrew the rear cover of the parent unit with a Phillips screwdriver.

2) Remove the rear cover.

3) Disconnect the old, non-functioning battery from the connector by hand.

4) Plug the new working battery back into the connector by hand.

5) Screw the back cover back on.

b) Baby unit

1) Unscrew the rear cover of the child unit with a Phillips screwdriver.

2) Remove the front cover.

3) Disconnect the old, non-functioning battery from the connector by hand.

4) Plug the new working battery back into the connector by hand.

5) Screw on the front cover.