Check the opener model and battery type in the owner’s manual or on the unit label
Disconnect power to the garage door opener if required by the manufacturer
Open the battery compartment on the opener unit
Remove the old battery
Note the battery orientation before removing it
Insert the new battery in the same orientation
Close the battery compartment securely
Restore power to the opener if it was disconnected
Test the opener and remote to confirm proper operation
Dispose of the old battery according to local battery recycling rules