VDB750 Video Works but doorbell/light don't

This is bizarre and can’t find any similar problem online about it. I have two VDB750 video doorbells. Both have been installed about a year and have worked fine until today. One of them, it seems, no longer lights up (the once-green ring, is now dark) and if you press the button it does not chime either outside or inside. However, the video is still working fully, live stream, etc. Therefore, I know it’s fully powered and connected to wifi.

The other VDB works perfectly as normal.

Any ideas??

If you temporarily remove that VDB750 from its mount and power it from 5VDC via the micro USB port, does the LED light up?