the remote that is NOT working:
move the switch to D* mode (if its not already)
open the door by the access card
get the last 6 digits of the number on the sticker above/below the access card
press mute+select on remote, light at top will flash twice after about 2s
press 9-6-1, channel up, light will flash twice again
put in the 6 digit number you got from the sticker
new remote should be programmed now
if that fails, use the working remote to go into settings > remote > advanced > ir/rf > choose rf from the drop down > program new remote from on screen instructions.