New firmware version BV6800Pro_S592_V1.1_20190320V23_20190320-1136 downloaded and installed on saturday, 13.
Problem solved: when I connect the phone to my car with the cable, Android Auto starts automatically and the display in the car show me all the functionalities without problems (maps, media, telephone, etc.). The phone is ok and there are no more accidental restarts.
Thank you, BV team!