After an engine swap/replacement vehicle ran, but now will not start?

Good morning,

Does the theft or security light go out after about 10 seconds with the key on?

https://www.2carpros.com/articles/how-to-reset-a-security-system

https://www.2carpros.com/articles/car-cranks-but-wont-start

Can you check the fuel pressure to see if the pump is producing the correct pressure?

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Can you check to see if it has any spark? When you crank the engine, does the tachometer on the dash move up a little showing RPM? That will tell me if the crank sensor is sending a signal to the ECM.

https://www.2carpros.com/articles/how-a-crank-shaft-angle-sensor-works

https://www.2carpros.com/articles/how-to-test-an-ignition-system

I would also check the compression to be sure the engine is not damaged internally.

https://www.2carpros.com/articles/how-to-test-engine-compression

Roy