Cannot get the Anti-Theft system to reset?

Roll up all windows and lock the doors with the key fob and allow the car to sit for 2 hours, then unlock the doors with the fob, and the system should be reset.

This guide can help as well:

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

Another way is to disconnect the battery overnight and reconnect it in the morning.

Also, you can try a hard reboot which is done by removing the negative side of the battery, with the cable loose from the negative side of the battery, hold it to the positive terminal for 1 minute this will discharge the memory capacitors in the BCM and PCM allowing the system to reboot.

Please let me know what happens.

Sounds good, please let me know.