How do I install new AAA batteries in the Stanley Fatmax Stud Sensor?

To insert two new AAA batteries into the detector, lift up the latch on the bottom of the stud sensor to unlock the battery compartment cover. Once separated from the unit, remove and insert the batteries with correct polarity as indicated inside (Figure B 3). Reattach the cover by inserting the pins at the top back in place (Figure B 4) and press down until it securely locks (Figure B 5). (Page 12)