Unlock the Padlock and pull the shackle to open position.
Turn Torx cap clockwise 90° with the Torx Screwdriver & push battery cover out.
Replace the CR2 Battery, close battery cover and turn Torx cap counter-clockwise 90°.
Push the shackle to close position to auto-relock or manual relock.

The following video provides a visual reference to how this is done!