How to resync a garage door keypad?

To resync a garage door keypad that has lost connection to opener and no longer opens door with PIN, you need to reprogram keypad to opener using Learn button on opener motor unit, which syncs rolling code security. First, locate Learn button on garage door opener motor unit hanging from ceiling, near antenna wire and light cover, often under light lens, colored yellow, purple, red, or green depending on model. Press and release Learn button briefly, LED will light steady for 30 seconds indicating ready to learn new device. Within 30 seconds, go to keypad outside garage and enter your existing 4-digit PIN or new PIN you want to use, then press Enter or Send button, and hold until opener light blinks, clicks, or garage door moves slightly, indicating keypad resynced and learned. For some models like LiftMaster 877MAX, you press Learn button, then enter PIN and press Enter, then press Learn again. If keypad has battery, ensure battery fresh, as dead battery prevents syncing, replacing with 9-volt or AAA costing few dollars. If wall console is in lock mode that disables keypads, indicated by blinking light, press and hold lock button for 5 to 10 seconds to unlock before resyncing. After resyncing, test keypad by entering PIN and pressing Enter to open and close door several times to confirm sync holds. If keypad still fails, it may be damaged and needs replacement costing 30 to 60 dollars.