Ensure all AXS components are “asleep”. Close the app and swipe away completely. Temporarily turn off Bluetooth on your phone. Ensure no other devices are connected or can be connected to your AXS components once they are awake (bike computers, iPad, trainer, etc.). Then…
Hold down the AXS button on the rear derailleur until the LED blinks green, then hold down the AXS button on the remote/shifter until the LED on that blinks green. Then push the AXS button on the rear derailleur a final time and both LEDs will turn off. This should mean that both units are paired and good to go.