2017 SUBARU LEGACY Exterior Lighting Problems

The car had been going on several local stops. Car was in the middle of a main thoroughfare ready to turn on to interstate ramp when the car completely stopped functioning. Battery light came on briefly before the vehicle became completely non-responsive. Among other things non-functioning, Emergency lights would not work, electric park brake would not engage. Could not get out of car to flee danger as car would freely roll and no way to stop except to hold brake with foot pressed. Ultimately car was chocked and jumped by AAA tow truck. Technician said battery was dead but alternator was working when he started it up. After 3 days of diagnostics, Subaru dealer cannot find a fault which let the new auto battery simply drain to nothing state and thus make the car non-responsive. Thank the good Lord this did not happen after turning on to the interstate.