ac sudenly quit working when battery died. replaced battery still not working. ac repair shop couldn't find what's wrong. Any Ideas?

The air conditioning system can quit suddenly for multiple reasons. But first -- is it an air flow problem, meaning it's not blowing any air? Is it blowing only hot air? What happens when you adjust the temperature? There are multiple systems at work here, and what must be done is to try and figure out which one is malfunctioning and then troubleshoot from there. Since it happened during a battery concern, I would look for any blown fuses that could have occurred if electrical components were jumped or accessed.