Chevrolet 2006 HHR Owner's Manual page 96

Manual Liftgate Release
If the liftgate cannot be opened by pressing the switch
on the outside handle, the battery may be run down.
See Jump Starting on page 5-33.
To manually open the liftgate, do the following:
1. Remove the trim plug, located on the inside of the
liftgate near the center, using a flat-bladed tool
such as a screwdriver.
2-14
2. Locate the release lever on the latch with a
flashlight. The lever is located about three inches
behind the trim in the access hole.