Mis change into 1st gear at a guess. Put it in P shut down, have a coffee for an hour and come back to it. Did the clunk happen when you engaged 'Sport'? I think so......... but.....?
Why cant you use the cigarette lighter socket - I used it for 6 years with the Macan. Plug in close the door. forget.... Itknows that it has incoming and stays live as opposed to outgoing when it shuts down............................