I am unable to open the rear passage door because the lock is broken and need to get the panel off without opening the door

 

Well, so ?
Sure your 2007 is an XG350 ? Production ended 2005.
Anyway getting door panels off with door closed usually implies destroying it. Hyundai traditionally bolts it on from the sides which isn't accessible with door closed.

I'd start with rolling down the window and try to see inside the door with a 'snake cam'. Maybe you get some access by removing the handle surroundings.