Can some please tell me how to get to the "secret" or secondary screen to the brake override on the Jensen VM9215BT? It's not the same as the others. The 533210 doesn't work nor can you hit stop twice enter 1264 and hit down button. What down button? The only knob on the unit is the volume one that only turns left or right. No joystick. Someone please help! Again it's a vm9215bt. Not the vm9512.... Anyone please??