Q: i have 2 of these remotes, bottom button will make led light up, top button does not, what are the functions of each? I have gone through the programming procedure and neither remote will respond to opener. batteries in each both show 2.9 volts
A: The two buttons have the same functions. Both buttons can be programmed to operate two separate Marantec openers.
Usually when the top button doesn't make the LED light up but the bottom button does that's a sign that the battery is low. It also could just mean that the top button is worn out.
Try programming the bottom button to the opener.