My 2015 leaf s is 3 weeks old with less than 700 miles. i was descending an 8% grade hill in b mode with a sharp bend at the bottom. as i went to apply the brakes, the pedal went to the floor and b mode cut out. the car was now rolling down the hill and accelerating under gravity with no brakes and without b mode slowing the car. i was expecting to hit a brick wall at the bottom of the hill when suddenly, after no more than two seconds, the brakes and b mode came back on and i safely stopped. on reflection after the incident, it was as if the whole computer/electronics momentarily shut down and then rebooted. i didn't notice if the dash lights went off or not. *tr