Astroflex Series 120 Not Working, 1997 Jeep Grand Cherokee

Hi. I have been trying to help my father in law with his 97 Grand Cherokee. We replaced the vehicle battery and since then his remote starter does not work. Nothing works on it, including locks, panic or starter. Lights on the fob do flash normally. To be honest, I am not sure if the kill switch was turned off or not when we switched the car battery. I have tried reprogramming the fob and per the led lights, it seems to connect with the main module as they flash. But there are no other indications of a connection, as neither the antenna or parking lights do anything. The antenna does not have any lights flashing at anytime. The code I get from the main module is 16 led light flashes but I haven’t been able to find what this means. In other astrostart manuals, that code indicates any internal module failure, but I am not sure what that would mean. Appreciate any advice anyone can provide. Thanks.

The remote is an Astroflex series 120.