My opinions are two folds here. 1.) For hand brakes Pull the hand brakes up and the warning light pops up on the MID , now slowly release the hand brakes and watch the MID warnings. Stop at the point where the MID warning disappears and at that point check the angle of the hand breaks to confirm that its indeed fully down. 2.) For doors Try taping the door locks ,give it a nice thick wrapping and then close the doors. Try these 2 tips and see if you still get the MID sound. - - - Merged Post - - - most probably the ECU is thinking that it's doing something unconditionally. Chances are , if all else fails you can try an ECU reset and see if this thing still continues.