I have a similar issue. My chime stopped working without reason (noticed that the sound would only come from phone-app and not the Wifi Chime).
First, tried re-connecting through the APP - no improvement
Second, tried to re-enter setup mode (press reset for 5-seconds). The chome would not enter the slow flash (got 3 quick flashes)
Thrisd, tried to full reset (press reset for 15-seconds). Again, only 3 quick flashes. No improvement.
Fourth, tries removing from power and removing the plug at the back of the unit. After several minutes, plugged back in (nothing, retried the above steps, still nothing).
Brian