Chevrolet 2008 Owner's Manual page 92

The lever is located about three inches (7.62 cm)
behind the trim in the access hole.
3. Insert a tool into the access hole.
2-14
2. Locate the release
lever on the latch.
4. The liftgate will unlatch when the lever is pushed
rearward. Push the liftgate to open.
5. Reinstall the trim plug.
Push the release lever
rearward.