I posted on this very issue on a different thread a while back. The L1011 used electrically operated actuators on the HP Cock on the engines, the fuel emergency fire shutoff valves, the engine pneumatic bleed valves and the pressurization outflow valves. There were NO mechanically actuated valves in those systems. In the event of the loss of electric power you could not:
Shut down the engines
Shut the engine pneumatic bleed valves
Shut the packs down
Operate the outflow valves
Cabin pressure (assuming the outflow valves were not already full open prior to loss of electric power) would prevent any of the eight passenger doors, cockpit escape hatch, baggage doors, galley service door or external access doors to FESC, MESC, hyd compt, etc. from being opened. That's because they were all inward opening doors. The pax door actuator did not have enough power to overcome the pressurization load. The doors are big, lots of square inches of surface area producing a lot of force holding the doors closed. That's why that planeload of pax perished when the fire killed electric power. No way to open any door from the inside or the outside.