The first thing to notice is the lock and unlock icons located on the left and right sides along with the index lines that line up with the icons. Next, there is a rectangular lock release hole located on the bottom edge to insert a small slot screw driver to release the locking tab. Pry toward you to unlock the tab and while holding that pressure, slide the front faceplate of the keypad up until the side index marker lines up with the unlock icons on both sides. The front face can now be separated from the back plate of the keypad to expose the batteries. The red tamper LED will be illuminated with the keypad open.
When assembling, line up the unlock icons with the index line on both sides first, then slide the front face down until the index lines are even with the lock icon. With the keypad closed, the red tamper LED should go out.
I recommend you not screw mount the keypad to the wall, instead use two strips of Velcro only on each side of the keypad so it can easily be taken outside when range testing camera locations. Do not place Velcro on the center of the backplate! It will permanently damage the tamper switch when pulled off the wall due to the outward flexing of the backplate.