Hi there! Have you tried performing a factory reset on the AirPods? This allows the case and each bud to re-sync. Also, while reestablishing the connection with your device, the AirPods will automatically update the firmware if there is one available.
Follow the steps in [link|https://support.apple.com/en-us/HT209463|this guide|new_window=true] and please write back if you have any difficulties!