Would a bad spark plug prevent the vehicle from starting?

Hello,

Generally speaking, an engine will need spark, fuel and compression to start.
So, if the spark plugs are not producing spark, then yes, it won't start.
However, there are a number of reasons why an engine might not start. It could be the spark plugs, also it could be due to a fuel delivery issue or compression.

https://www.2carpros.com/articles/car-not-running-advanced

Is it cranking over and not starting?

Let us know a little more details of what you are experiencing.

Thank you.

Follow that guide I provided you on the first response. It will walk you thru how to check for spark, fuel and other crank no start issues.
Let me know what you find.

If the security light flashes then the immobilizer might be triggered.
Try disconnecting the battery for a few minutes and reconnect and see if that resets the light.

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