Head lights fade, engine pops back and shut off.

Is there a reason that you are thinking this is a security issue? Is the light staying on or flashing?

I would suggest we start with checking for codes and see what is there.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Also, if this is a security issue then this guide will help with the basics to find out if we can just shut it off:

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

If not then if the headlights faded, that sounds more like a battery or alternator issue.

So we need to get both of those tested as well. Here are guides that show how to load test both.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

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

Lets start with all this and go from there. Thanks

Okay. if the theft system is on or flashing then that is preventing the start.

I assume you are using the remote to unlock it and it does not work? What about unlocking the door with the key? If that doesn't work then we may just have an issue with the door circuit so here is testing. However, I would start with checking for codes because if there is an issue with the system it should have a code.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Let us know what you find with this and we can go from there. Thanks