Long press volume key, and check LINE OUT.
The MN312R has Low Level Audio output. If desired , press and hold the volume button on the mirror then select “Audio line out”
Check and make sure the temperature probe is connected completely to harness.
Need to relocate the temperature probe to different location, making sure it is away from any type of heat source.
Make sure your phone Bluetooth is in search mode and discoverable. Also need to make sure your phone is not connected to any other Bluetooth source.
This is a common issue with Android phones. Even if the user deletes the Bluetooth address from the phone, the phone will still remember and reconnect automatically.