won't crank after a battery and radio swap?

I do not expect the radio to be the cause of this. The battery being replaced has been known to cause the theft system to go active and then the vehicle will not restart when the battery is hooked back up. When you turn the key to the on position does the theft light turn off or does it stay on or blink? This sounds like the starter is having problems or the battery needs to be load tested these guides can help us fix it.

https://www.2carpros.com/articles/starter-not-working-repair

and

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

Please run down these guides and report back.