Advanced Key Battery Replacement [Advanced Keyless Entry And Start System]

Pull out the auxiliary key.
Insert a tape-wrapped Flathead screwdriver into the notch in the advanced key and rotate it in the direction shown in the illustration to open the advanced key.

Fig 1: Pulling Out Auxiliary Key
Courtesy of MAZDA MOTORS CORP.

Fig 2: Opening Advanced Key Using Screwdriver
Courtesy of MAZDA MOTORS CORP.
Remove the battery cap.
Remove the battery.
NOTE:
- If the O-ring has come off, put it back in place before installing the battery.
  
  Fig 3: Removing Battery Cap
  Courtesy of MAZDA MOTORS CORP.
  
  Fig 4: Identifying O-Ring
  Courtesy of MAZDA MOTORS CORP.
Install the new battery (CR2025) with the negative pole facing down.
Install the battery cap.

Fig 5: Installing Battery (CR2025)
Courtesy of MAZDA MOTORS CORP.
Align the upper and lower covers and close the transmitter.

Fig 6: Aligning Upper And Lower Covers
Courtesy of MAZDA MOTORS CORP.
Insert the auxiliary key.

Fig 7: Inserting Auxiliary Key
Courtesy of MAZDA MOTORS CORP.