There is a pin just above new inserted film cartridge. It signals to the camera that the door is closed or open, so it moves in and out the camera body.
When you are closing the door, it is pushed in. At the same time the door lock slightly push the door downward, so the pin gets bending while closing the door. It can damage the switch that pin activates. In such a case camera do not function and has to be repaired (not an easy and simple).
To avoid this potential problem try to pull out rewinding knob while closing the door, in the same way when opening the door.
This is not design fail, but rather a way of living with F6.