Nope, most systems are available once power is turned on, and you have ground power connected.
Remember of a case of airframe with engine removed, and tanks part full. Power applied, with the LP cock switch inadvertently turned on, and the motor operated valve turned to the open position to comply, and dumped all 6kl of fuel into the inside of the airframe. Turn power off and still fuel flow, because the design is such that the engines will keep running even with total loss of power, thus the motorised valving. 10cm diameter pipe and valve does flow very rapidly, even without the LP pump operating, as it is in the lowest part of the airframe to make it self priming, and is just below the bottom of the wing tanks. inside and floor was very clean afterwards.
Armaments systems are available with power applied only, only thing with safety interlocks are ejection system, because it is not power operated but pyrotechnic, and thus needs the mechanical interrupts to prevent operation by accident. Vulcan cannon might not have run properly without hydraulic power, but the firing circuits for the 20mm shells are electric, and mechanically applied to the cartridge when in position and ready to fire. It would have fired, though possibly not at full speed.