Hold down the power button for 10 seconds to reboot it.
BTW just switching the car off, locking and unlocking doesn't shut it down completely. It takes leaving it for some amount of time I've never figured out, but longer than 5 mins.
Problems with MIB crashes are as old as the Mk7.
Sometimes a software upgrade can cure it, but often not and its not your particular unit either, so swapping it out won't make any difference!