Ran hot switched off; will not crank up any ideals?

https://ibb.co/f03SZVv

Click on the link, the diagram is for starter motor. Will the starter motor crank the engine? If it cranks good but won't start, make sure battery has a full charge and connections all good. Have a helper crank it while you check for spark at the plugs. Spark everywhere, use a gage and check proper fuel pressure. Check fuel injector pulse. Any applicable trouble codes. Those are the basic checks, in my opinion.

All I can say is he left something disconnected.

There is a fuel inertia switch..that is the law.. It is located either outside by the connections to the fuel pump or on the pump itself. I doubt that is the problem as you say the pump is pressurizing. May be a security system issue or pcm issue.. GM cars are very sensitive to voltage changes of any type...Take it back to the mechanic.

hit the fuel pump rest switch it cuts spark and pump

I’m happy to assist further over the phone at https://www.6ya.com/expert/james_1cb31da1bc8c6102

Starter solenoid may be bad.

the engine is probably seized up

bad ign.switch

could be fuel filter or injectors. Might be the throttle actuator.

you should always put water in a overheated car with the motor running sounds to me like cold water in hot engine syndrome unfortunately this is fatal to the motor most likely cracked heads

Try the electrical iginition switch, and the "candybar" on the front of the distributor.