Remove the batteries from the Firestick remote
Unplug the Fire TV Stick from power
Wait 60 seconds
Press and hold the Left, Menu, and Back buttons together for 12 seconds
Release the buttons
Reinsert the batteries
Plug the Fire TV Stick back in
Wait for the Fire TV to finish restarting
Press and hold the Home button for 10 seconds to re-pair the remote
If needed, replace the batteries and repeat the pairing step