Does the plenum hum? When these engines are ready to start, there is a distinct mechanical hum coming from the top of the engine - I think it is the throttle motor or similar. No hum = ECU not getting power. I know the relay layout by heart on the 155 V6, but not the 24V, but you could have a dying relay in there. Generally the model is one relay powers up the ECU, and then power cascades from there to power up the fuel pump and everything else. If the first one is flaky, then you get nothing - the one thing that does not match is the behaviour of your starter motor. You can kill pretty much everything and the car will still crank - it won't start, but it will turn until the battery is flat.
Given the starter behaviour I'd be looking at the grounding of the engine. Check and clean: battery to earth, earth to gearbox and the coilpack earthpoint on the RHS of the front head. Problem on the 3.2 is checking the connections to the positive side of the starter - pretty much impossible with the engine in place. Also check the battery positive clamp - on my 2.5V6, this sheared to the point where it could run the car, and get the lights on, but not start it.