I am sure there are a series of special engineering functions that you can do by pressing the 'power-on' button in certain ways.
Does anyone know for sure/have a list?
I know that there is a feature where you press the power button in certain ways to enter 'dealership storage mode', but don't have the details of that. This turns off all the active 12V circuits when OFF.
I came across another one purely by chance the other day. I had run MM and then pressed the power button while still in drive, it gave an error and 'shift to park' and when I did I got the ERDTT message and the engine sprang back to life. It was 8C!
Strange things happen when you press that power button in certain ways. I suspect there is a number of 'special modes', either deliberate or accidental, or probably both.