I'm saddened to hear that your device will no longer pair after the software update. I would like to attempt some troubleshooting steps with you to see if we can rectify this situation. Can you tell me the make and model of the car?
I'm sure you have fixed your problem by now, but maybe this could help someone else... I had a similar problem with my S20+; I merely had to delete the device from my car's Bluetooth and then re-pair it to the car. That should/might take care of the problem.