Audio not working on Ring doorbell 4

When I watch back videos on my ring doorbell 4 I’m unable to hear any sound whatsoever. This has happened since we’ve had extremely cold weather recently and the camera has fogged/frozen over during the night. I’ve tried resetting it several times, taking the battery out and swapping it for the spare battery I have as I happen to have two batteries, but still no sound. Videos are still clear i.e. it is picking up motion etc. just no sound. It was purchased in August 2021 so unfortunately now out of warranty. Anything else I can try to get the sound on videos etc. working again or is it a lost cause?