This evening I dropped by the hangar, flipped the battery switch on and the
  hydraulic pump ran constantly, as if the alternate extension bypass were
  open.  It wasn't. 

Naf,

 

One further thought.  After the accident, perhaps one of the actuators (especially in the nose gear) may have had a piston seal completely fail - thus, this would allow fluid to flow by the piston and the system would never reach a stopping pressure.