How do I get in my locked trunk to get and replace disconnected battery?

if you are sure the positive battery cable in the trunk is NOT touching metal or the negative cable,then hook up jumper cables to the jump points under the hood from another source. this should give you enough power to open the trunk!

Insert your ignition key into the manual trunk lid lock located in between the XK8 letters on the trunk lid.

You can use your ignition key to unlock the trunk. The key hole is hidden in the XK8 emblem on the right side of the trunk. They did a good job hiding it.