Catalytic converter and auxiliary battery relation

Dear frds,

I hope you doing well in this pandemic.
Recently I found out my prius 2009 was making a weird noise. I looked under the car and saw exhaust manifold bolt and spring fallen. I did some research and found out that my catlytic converter was stolen and hence the motorcyle noise from my gentle car. But also after 5 minutes of finding that, my car won't start on with the power button or the switching off wont work. Then eventually it just died on me. So now my insurance covers the theft but they say they won't cover anything else. I took to the toyota dealer and they diagnosed that my auxiliary battery is not good anymore thats why the car won't start. So the other repairs I need to pay. So my question to you guys can the auxiliary battery die suddenly when the car was working fine completely before the theft. Can I link it anywhere related with the cat theft. Thank You!
Hope you all keeping safe.