Could be lost residual power when battery was changed. May need to reset fobs to car. Check out the " stickies" on the top of this forum, page #1 . look for key reset instructions. I believe you put key in turn to on position, wait until all dash lights go out, turn key to off. Wait 10 sec. And do it again. Then a third time. But after third time start car. Then repeat with second key. Better explanation in the "stickie". Good luck.
Back in the day when I installed aftermarket alarms. One had to press the unlock or lock at least 5 times before the alarm would react.
This was true wether the battery in the car or remote was replaced. And it didn't matter how long the said battery was out. I've actually removed an alarm from one and put it into another. It took over a year to do that process. But they still talked after those 5 or more presses on the remote.