When trying to set up a new Overhead CodeDodger wireless keypad (with buttons for “SET” and “PRGM”), it is very important to understand what the instructions mean by an “open” case. This is best seen at night when the buttons light up.
In the three pictures below, the case goes from closed, to open, to off. The huge difference is “open” versus “off”. Looking at “off”, there is a button on the top left of the wireless keypad. This needs to be pressed in, and it is pressed in by the case cover. You can see a nub on the case cover that will press that button in. When in position “open”, that nub will push in that top left button, and at night, you will see the keypad light up. Credit for RTKNJ for this amazing advice.
With this knowledge, you can follow the instructions found elsewhere, like here and here.
Last note, if you see the backlight on your wireless keypad, you do not need a new battery.