Chevrolet 2005 Corvette Owner's Manual page 123

If the vehicle has lost power, the convertible top can still
be raised by releasing pressure on the hydraulic pump,
located in the engine compartment on the passenger side
of the vehicle, by using the following steps.
1. Raise the hood to the engine compartment.
2. Locate the pressure release bolt on the front side of
the hydraulic pump.
3. Use the wrench, attached to the inboard side of the
hydraulic pump, and turn the pressure release bolt
counterclockwise one revolution, to relieve
pressure to the hydraulic pump. This will allow you
to manually raise the convertible top.
4. Then follow the steps under raising the manual
convertible top. See "Convertible Top (Manual)"
under Convertible Top (Manual) on page 2-55
or Convertible Top (Power) on page 2-62
When power is restored to the vehicle, the hydraulic bolt
must be tightened, by turning it clockwise. The power
convertible top button can then be used to lower or raise
the convertible top.
If the power convertible top is operated multiple times,
the engine should be running to prevent drain on
the vehicle's battery. Under certain conditions, the Driver
Information Center (DIC) may display a message
regarding the power top. See DIC Warnings and
Messages on page 3-53 for more information.
2-65