Buick 2004 Rendezvous Owner's Manual page 102

Liftgate Release
Liftgate Handle
2-12
Your vehicle is equipped with a liftgate release touchpad,
located on the inner side of the liftgate handle.
To open the liftgate using the touchpad, do the following:
1. Put the vehicle in PARK (P).
2. Unlock all of the doors.
3. Lift up on the liftgate handle.
If your vehicle has a remote keyless entry transmitter,
you may unlock the liftgate by pressing the REAR button
on the transmitter, then open the liftgate manually by
lifting up on the liftgate handle.