If you take off the small window rubber at the top of the door when it's open, with a flashlight you can see if the rod is connected to the handle button.
I think it's the latch mounted on the door that engages on the latch post mounted to the body where the door shuts. There is a spring inside that little box. You should be able to release it with the door panel removed.
chevy runs deep, Don't step in chevy!
67 Coupe 289 - TCI C4 w/2k stall; Holley 4150 570cfm; Performer intake; mild cam; Pertronix HEI; 302 heads; Roller Tips; Hedman Tri-Y headers; H-pipe w/Flowmaster 40's; 9 in posi 3.50; 205/50-17F; 225/50-17R.