Keyless Entry Remote Battery 2002 Ford Mustang: Replaced Keyless Entry Remotes Battery But Now It Doesn't Work?

2002 Ford Mustang: Replaced keyless entry remotes battery but now it doesn't work? - keyless entry remote battery

I recently replaced my battery and now Mustang keyless entry remote no longer works. My Mustang has an alarm, even though I am not sure whether the mark, since it was installed before purchasing the car. I can not set the alarm and unlock the car with the remote factory, and need help! Thanks in advance