The key fob will need to be reprogrammed to the vehicle as when the battery was replaced in the key fob, the key was reset. This is why nothing is working with the key fob. After replacing the battery in the key fob remote, you will need to reprogram the remote to the vehicle.
Secondly, how do you reset a key fob? Insert your key into the ignition turn it to the On position — right before actually starting the car, the lights should turn on. Press and hold the Lock button on your fob remote car starter for one second. Turn your key to the Off position — the car lights should turn off.
Keeping this in view, why does my key fob not work after replacing battery?
The most common problem with these car key fobs is that the batteries just go dead over time, in which case replacing the battery should fix the problem. Take the key fob apart and check for broken contacts or misaligned buttons. Reprogram your remote yourself or have a professional do it.
How do I reset my Chrysler key fob?
How to Program a Key Fob for a Chrysler
Turn your cars engine off and turn the ignition to the key run position. Press and hold the unlock button on your functional key fob. Release both buttons simultaneously.