Sync Module no longer ringing.

Hi. I have a blink door bell and sync module, purchased just under 12 months ago.

Until recently, when the door bell was pressed, an audible tone would come from this, the app, and sync module. However this week, the sync module has stopped doing this.

I have changed the batteries in the door bell, thinking that might be a problem. I can't find anything within the app to manage the module.

Can anyone offer some advice? Thank you.