batteries must all point in the same direction, with the positive
(raised tip) ends facing down (towards the tip or lens of the
swing the club the inertia of the batteries can cause the springs
in the battery holder to compress, breaking the electrical contact.
This is why the battery holder springs are both at the top.
Unscrew the locking screw.
Remove the covers top and bottom.
Remove old batteries and replace with new ones making sure that all
four batteries are facing in the same direction with the positive towards
the electronics or lens.
Replace the covers and tighten the locking screw.