Volvo Penta MD2020 engine won't start

[Sindbaad]

Motoring out of the harbor noticed thick black smoke in the engine room. To cut the long story short it was a fractured exhaust riser that allowed smoke and water pour into the engine compartment.
After cleaning up started the engine with the sea water cock closed. It started. Shut it quickly. The boat was towed into the harbor. Since the engine turns but does not fire.
I have checked the choke; it i fully depressed, checked glow plugs; all normal reading. Charged the start battery full. Changed fuel filters and tightened all hose clamps. bled the system all the way to the injector pump. No results. Is it possible that the fuse on the engine block has shorted?
Any suggestions how to deal with the engine that does not start?
Thanks for all help.