Hey bobspryn,
I think it has to be the power button, since it goes directly to AVR Mainboard (and this is what you pull when you pull the panel with the connectors). The advantage of the pushbutton is you can remove its back portion with the wires, but of course only by opening that panel. Maybe that is the reason why they made the wires of power button shorter than on rocker switch. If you open the panel with the push button, and remove its back portion like shown in the this video, do you have any additional other wires being too short to access the SD card?
EDIT: Just realize they produced two new videos on how to access the SD card, separately for pushbutton and for rocker switch version 
Now the panel with the connectors is recommended to be loosened in both situations (rocker switch version video / power pushbutton version video).