Will not crank, alarm (horn) beeping

I wouldn't jump pins for the ECM do you have a security light flashing? If so this guide should help us:

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

Also lets check the battery condition this guide will help:

https://www.2carpros.com/articles/car-battery-load-test

and

https://www.2carpros.com/articles/starter-not-working-repair

Please run down these guides and report back.

The factory system is integrated into the rest of the car and there is no way to bypass it. Is the theft security light on? Does it go out as soon as you try the key? If the light stays on then there is an issue in the system, if the light goes out when the key is in then there is a different issue than the anti-theft.
What you can try would be to disconnect the battery, then short the battery cable connectors together for a few minutes, that will drain off the capacitors in the system. Reconnect and see if anything changed. The next step would require a dealer level scan tool to determine if the anti-theft or the ECM itself has a problem.

That doesn't sound like a factory system. They don't have an individual fuse for the alarm like that as it's part of the circuit that powers the engine controller and the transponder system. But it's running. I would be real careful though, if the system locked it up that way once I wouldn't trust it to not do it again.