I WAS AT A STOP SIGN IN MY 2020 HIGHLANDER WAITING TO TURN LEFT ONTO A BUSY ROAD. UPON TURNING LEFT ONTO PA STATE HIGHWAY 999, THE HIGHLANDER ENGINE TURNED OFF AND THE STEERING WHEEL WAS "LOCKED" INTO A LEFT POSITION. THIS CAUSED THE CAR TO CONTINUE TURNING INTO THE OPPOSING LEFT LANE RESULTING IN A HEAD-ON COLLISION WITH AN ON-COMING CAR. WITH THE ENGINE TURNED OFF THERE WAS NO POWER STEERING, NO BRAKES, AND NO WAY TO UNLOCK THE STEERING WHEEL. THE COLLISION CAUSED MY CAR TO BOUNCE BACK AND SLOWLY FREE ROLL BACK TO THE STOP SIGN AS THOUGH I NEVER ENTERED THE ROADWAY.