OK, I'm an idiot. I was working on a door lock problem last night and not wanting to drain the battery while I left the door open overnight, so I disconnected the battery - then closed the trunk lid. The car is new to me so I didn't even think that there would be no key release at the trunk......
Can I apply power somewhere to restore momentary power to get the trunk open?

Any advice would be appreciated.

 

The key release is beside the rear XJ8 badge.

 

I have the XJR R edition, no key hole I'm afraid. I did resolve it by applying 12VDC in the engine compartment and used the fob to pop the trunk.

Thanks!

 

Yeah, that should normally work.
However, as there was no "R" version of the XJR, I presume someone put an aftermarket decal / sticker / badge over it, the hole for the key should be underneath.
Not a bad idea to restore it to the original, you never know the next time you will need it .
Oh yeah, check if it works, they used to gum up, can be worked loose with WD40, then use graphite after everything is dry.

 

After really LMAO I went out and looked and felt behind the liner and low and behold!
I really know VERY little about these cars :-)

 

Ha, someone filled up the recess...now , you are lucky the hole is still there then ...
This is how it looked ex-factory for a XJR:

 

Thanks Eric!

 

"And I now see" said the blind man lol, this forum is awesome.

 

Ypu can also apply power in the engine bay to the main terminals and like that feed the boot unlock system

 

Unless you had left the negative cable resting on the positive post to do a hard reset prior to the lid closing. Things get rather warm quickly if you try it then.

 

I got myself into a similar situation last summer when I locked my keys inside the trunk. Wound up having to drill a hole behind the license plate to pop the release. Consider yourself lucky!

 

If you take a straight edge and make an X in the middle behind the licence plate you will be in the exact spot to drill a hole to be able to lever over the trunk release , been there , done that . Use the 4 plate mounting holes for the corners of the X . Same on X300 and X308 .