For those of you that have the Jaguar flip out Ignition/door key and need to know how to change the fob battery here are the instructions
You will need a small crosshead screwdriver, a small flat blade screwdriver, Replacement battery.
This task should ideally be completed within three minutes of removing the circuit board
First remove the key from the Fob by inserting a small flat screwdriver blade into the slot in the fob assembly and push toward the key. Always point the key away from yourself to avoid injury.
Separate the two halves of the fob by inserting the screwdriver into the fob as shown right and lever gently backwards.
Try to complete the next task within three minutes between removal of the circuit board and re securing it after the battery has been changed.
Remove the screw from the circuit board and lift the board away avoid touching the components and handle at the edges only. Take care also not to touch any connectors.
Flick the battery out of its retaining springs and discard. Fit the new battery with the side marked with a positive downward. Avoid touching the battery with your fingers as oil and moisture can reduce its performance and life span.
Reassemble in reverse order; replace circuit board and secure with the screw. Fit the back of the fob and click into place with finger pressure. Finally slide the key back in until it clicks into place