These are the steps for changing your AirTag’s battery: 1. Make sure the stainless steel side is facing you. 2. Press down on the stainless steel backing. 3. While doing so, rotate the cover counter-clockwise. 4. Pull the two halves apart. 5. Replace the old battery with a new one, with the + sign facing you. 6. You’ll hear a beep when the AirTag resets. 7. Replace and align the cover. 8. Rotate clockwise until it stops. Your AirTag should be at full power now. If not, you either have a drained battery or the AirTag is malfunctioning.