”He” would be pretty long in the tooth since most cars for the last 30 or more years had fuel injection. I would go to another shop.
It could be a shorted wire in the ignition, injector circuits supplied by the am2 fuse. The ignition switch is part of the circuits, and fuel pump. The am2 is ok? Then the fuses after the am2? The basics of spark, gas, and air still apply. If it has those it fires. Need a wiring diagram. If all fuses good and no shorts, go to each component and test. I’ve seen people furiously pumping the gas when their newer car won’t start. Like was said, those days are over.
I don’t know about the Prius 30 (I haven’t dealt with this yet), but the symptoms are similar to a clogged exhaust system. A melted or broken catalytic converter that has blocked the exhaust. You can remove the air/fuel ratio sensor or one of the spark plugs, also disconnecting the coil, start it and see if the engine would run any longer. Also you can check the pressure in the exhaust system by installing a pressure gauge into the place of the air/fuel ratio sensor.
Final update to this diagnostic challenge... The guy I was advising on this challenge exhausted all the options on here regarding things to check and finally took it shop and $600 later they found the problem to be: "an air hose into the fuel mix place which had a leak in it" Not sure what exact part that is but I suspect it might be what mechanics call a vacume leak from a failed hose. Anyways, hope this helps someone who might one day have a similar problem... In hindsight, if I could help with this diagnosis all over again I'd be wiggling hoses in engine compartment in search of a vacuum leak while engine was attempting to start via electric motor. I've seen mechanics find the source of the problem so many times with that method and instead I forgot all those experiences and was dumbly staring at Toyota Techstream screen wondering what the problem was.
This is why it's recommended to change many of those cheap hoses out during the first major EGR cleaning like the Hybrid Pit does. It adds some cost to the job but could save all this trouble later.