the metal circular doo-dads on the control panel pull out and up to lift the panel after unlock. I have a ring edge in mine right now for tennis.Snapped a photo of the inside of the back panel last night, looks like the attached photo.
Cereth also did a nice overview of the cabs on youtube here:
I'll be studying it to see what I can learn. Right now I have no idea how to get into the control panel lol.