One failure mode of the 944 S2 and 944 S DME/ECU is no ignition output.
I have seen several die like this, which is why I always kept three loan S2 DME on the shelf and used to sell them on an exchange basis.
Typically the two failure modes of the S2 and S DME is either loss of spark, or loss of idle, but loss of spark is the main one. Usually I think the repairer says it is the ignition power transistor within the DME which dies.
It could also be a number of other things, such as the crank sensor on your other thread.
Usually the Hall sensor on the cam pulley can be disconnected and the car will still run, but typically with a slightly rougher idle and stalling on return to idle at times.. This sensor is just used for telling the DME what phase the cam is at, without it being connected or if it fails, it will typically default to running batch injection rather like the 8v cars rather than sequential as it should.
Other sensors, the engine management coolant temp sensor can make cold starts tricky if that fails, which is near the other coolant temp sensor used for the dashboard, these are often failed and people do not know it... However, typically this would be hard starts rather than non starts.
Airflow meter is ignored during cranking, so it is not that.
Bad earth strap at the back of the engine can look ok, but actually have a big voltage drop between earth and engine earth if old, which can cause all kinds of problems during cranking, as the limited ground potential will allow the starter to have a good earth, but not the sensors which at best confuses the DME, at worst it can burn out your ABS sensor wiring loom, as that becomes the next best path to earth!
Other than that, it could be a wiring fault..
Does it try to start at all? Such as a cough as you let off of the key?
Alternatively the ignition amp as you say can be a problem, as can the coil, but it is relatively rare in my opinion (I have had to change 1 ignition amp in the last 28 years as a Porsche technician with a big 944 customer base, have changed several coils, but usually due to poor coil performance, not it completely failing which can be tested)
