So if I'm reading this right, with the ignition OFF, once the pressure is released at the bleed nipples, wheels rotate freely, still with the ignition off, you pump the pedal and still all is o.k, wheels move?
Next step, ignition on, engine off....... ,wheels move? ABS fault
Next step, ignition on, engine on......wheels move? ABS or Servo fault.
I know it's frustrating, but I don't think you have done any serious damage, just think the system needs pressure bleeding. As a long shot you could try pulling the ABS fuse or disconnecting the feed to the ABS pump and see if that works?
you cant powerbleed the system on the 350z as far as I'm aware..
Running the risk of being shot down in flames or eaten by Neil - You can't power bleed the clutch I think you can power bleed the brakes (I hope so I have )