Pontiac 1998 Firebird Owner's Manual page 130

If your vehicle has a power loss, such as a dead battery,
you can still raise or lower the top manually by turning
the
valve in the left side of the hatch.
.
Open the hatch and find the tab along the left side
t r i m
panel. Lift up the tab and turn the valve clockwise to
release the hydraulic pressure. Turn the ignition key to
LOCK. You can now raise or lower your top manually.
Be sure to close the valve after installing your top so
you can raise or lower it electrically later.
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