Locate the dial on the end of the ball, and use a quarter or other flat instrument to move the dial from ‘Locked’ to ‘Unlocked.’
Hold the ball in both hands and twist the sides in opposite directions as shown below.
Pull the blue side of the ball away from the center.
The battery compartment is on the inside of the white center piece. Remove the two screws in the battery compartment door, and replace the batteries.