2006 xk8 stop light on trunk lid does not light when brakes applied. How do I get in to the light to check for bad bulb, broken wire, etc.?

 

The common problem is a broken wire at the right side lid hinge from a few years of flexing.

I pulled the entire harness out and spliced it so that it was not visible. The next car had the same problem under warranty and the Jaguar tech cut the harness open and taped it back up for the world to see.