2006 Pontiac Grand Prix Won't start

Long story---car wouldn't start after getting off work, smelled electrical
burn...checked to see the issue, an ignition coil cracked and was smoking. I
replaced all 3 ignition coils and the ignition module and sprayed starting fluid
in the top of the air intake, still wouldn't start. Checked the fuel valve for
pressure, it has pressure. Checked the plugs for spark, it had spark. Took it
to a mechanic, and he replaced the crankshaft sensor...still won't start. He
thinks its an issue between the ECM (Computer) and communication with
one of the sensors...but doesn't think the ECM needs replaced. Ultimately it
has to be a wiring issue but that level of knowledge is beyond my
understanding. At current, my car has been in the shop for a few days. If
anyone can give me any idea as to what the problem might be it would be
very helpful.