Have you actually checked a fuel line for pressure? If you have pressure in the supply line and injector pulse then i am happy with that. I believe you have spark. Which leaves only compression (if cam belt is still in one piece then it's hard to see any reason why all cyls have lost compression - you can tell low compression by the way it winds over)
One other thing to consider then:
If you for whatever reason had a lack of fuel to a cylinder (fuel starvation under hard acceleration?) a backfire through the intake isn't unusual.
A backfire through the intake can damage the "hotwire" in the AFM.
The AFM is the main signal used by the ECU (along with the CAS) to calculate a base fuel load and ignition timing.
If the AFM has been damaged by the backfire then it is unlikely your engine will run at all.
This happens quite alot to cars fitted with venturi type LPG kits (not really relevant here). LPG systems falls out of tune (lean), backfires, blows AFM apart, no go on petrol (runs on gas as gas processor doesn't need AFM to operate).
Anyway, your scan tool will tell you if afm is working or not.
cheers