@fredd60 has an X308 and is in the wrong Forum. Our X351 models don't have that access panel.

 

I haven't updated my personal details. Currently driving a 2009 XF. Have you checked to see if your X351 has that access panel?

 

No such panel exists on X351. No mechanical lock anywhere than drivers door.
The factory X351 Service and Repair manual give two options after accessing inside if the cabin with emergency key thru drivers door:
- Option one: Open hood and add power to the power point inside of engine bay fusebox and the press Open Boot button. Nothing else, donīt turn ignition On !! (also descripted on Owners handbook)
- Option two: Remove back seat and rest. There are an plug/wire to power only the boot lock solenoid. This is for the cases that battery are removed, trunk closed and battery Plus terminal shorts to chassis. -> vehcile circuit unusable.

XF is totally different chassis and its more worth to write tricks and hints on XF forum instead of XJ forum where they are unusable.