Hi there. Please allow me to assist.
First of all I'd like to make something clear; as experts on this site, our only goal is to help you solve your car issue, we are not here to belittle or criticize any one. We're just trying to help you.
Now, to the issue at hand; as expert Brooks indicated, the anti-theft system prevents cranking of starter and fuel delivery to engine. The cranking/fuel interrupt function operates independently of the alarm system and provides protection even if the alarm system is defeated and vehicle is left unlocked.
In other words, if you turn the key to START and the starter engages, the anti-theft is disarmed.
Also, as expert Brooks indicated, you need to jumper across terminal A and B of the ALDL in order to get codes. Terminals A and B are next to each other horizontally.
Lastly, it would greatly help us help you solve your problem if you tell us what condition prompted replacement of the ECM.