Alarm turns on when trying to start the vehicle

If when you turn the key to start the vehicle and the alarm is going off then the vehicle thinks you are trying to steal the vehicle.

We need to start by trying to deactivate the system. Here is a guide that will help with this:

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

Next we need to assume that the key is not deactivating the system. This means that the resistor in the key is the issue or the immobilizer is not picking up the key.

I am attaching the info required for this but I would suggest before we go much further that we check for codes. That can point us in the right direction and more then likely tell us what the issue is. Here is a guide to help with this:

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