05 S40 T5 Electrical Mess - Please Help!

Hey all, my father bought this car with damage from an interior fire. I come from the oldschool VW world, and am unfamiliar with these complex, computerized machines, thus I am doing this in hopes of helping him out. It looks like the wiring harness going from the interior fuse-box to the sunroof and vanity mirror had started this fire, as it was the only wiring which was found to be damaged. The damage extended right to the fuse-box itself, however, no other wires were affected. Only the sunroof area was affected by the fire. Currently, I have been trying to get the car started, as everything else will be a cakewalk in comparison.

So far I have swapped the fuse-box/ecu with a known working one from an equivalent, 06 model. When using the corresponding ignition key, I am getting an immobilizer warning from the trip computer. I can hear an electric pump (power steering?) of some sort turning on inside the engine bay, but the motor itself refuses to turn over. There is no audible evidence of the steering lock disengaging, and the stereo isn't turning on either. The windows all have power, but the front ones refuse to go down for some reason. They act as if they are physically locked in the up-position, although the motor does respond to the command.

Can you please explain to me which modules affect the starting of the car? Being an electrical fire, some of the sensitive circuitry might have been damaged, without physically appearing to be. I need some guidance, as I am now completely out of ideas. Any help is kindly appreciated.

Thank you.