MG5 won't turn off

[indycar]

This happen to me once, turned car on and started flicking forward and reversing quickly, to park in parking space, car just froze, was un-able to turn off -do anything. headlights on. After leaving it alone for 10-15min, car reset itself. This was about a year ago, has not happened again. I now do let the car start up properly before puting in gear, and not so quick between switching forward and reverse.