[Uhehner]

Probably need more information. Does the starter turn? Does it fire at all or just roll with the starter? Did your mechanic check spark, fuel pressure and plug into the diagnostic port to check for codes? I don't know that engine in particular but assuming it cranks and has spark, and no warning/diagnostic lamp maybe look at the fuel pump. A lot of MPI engines have a fuel pump relay and or an oil pressure switch that provides power to the pump when oil pressure is present.

I agree 100% with the above.  One more quick check --- can you hear the fuel pump run for a second when you
turn the key to ON ( not to START ). That will indicate fuel pressure.
Fuel pump relay failures are very common. I always carry a spare and they are cheap.
If the engine does not spin when you turn the key to START you most likely have a hydrolock and need to pull the plugs. Most likely cause is a hole in the exhaust elbow.
Capt. George