How to Change a Battery in a Nissan Key FOB
- 1). Place the edge of the screwdriver between the crack where the upper and lower pieces meet. Turn the screwdriver in either direction until the pieces separate.
- 2). Pull the key fob apart and set the pieces onto a table. Pull the battery from between the two upper pieces.
- 3). Insert the new battery between the two upper pieces. Make sure the battery is in the same position as the old one.
- 4). Reassemble the key by putting the pieces back together and applying pressure until it snaps back. Program the key according to the owner's manual.
Source...