Anti-theft security system

Changing the battery likely tripped the anti theft system, common issue on some modern vehicles.
If the security light is coming on when you turn the key then it no longer recognizes the key. Unfortunately the only way to reprogram the system is by using the dealer scan tool and dealer code to get the keys to work again. You can try to see if it will accept the key, Put a key that has been used to start it before in the ignition. Turn it to the "run" position not start. Let it set in that position for ten seconds. Now turn it off, and then turn it to the start position and see if it starts. If it does you should be okay. If it does not then the system has to be reinitialized using a dealer consult tool.

Good morning my name is Roy and I will assist as well.

Just to add what Steve told you, try procedure with the key. If that does not work, see if there are any locksmiths in your area that have the ability to program the key. If they do, then they can come to you and perform the procedure at your location.

Roy