The big black power brick is the 12V/5A supply that powers the Rambo. The RPi is powered by the smaller 5V supply. The outlet inside is wired up via an estop switch to an inlet in the back that takes a standard IEC power cord.
So, power comes through the power cord into the back of the controller. The hot line is routed up to the front through the estop abs back to the hit junction terminal (the one with the red tab). The neutral comes in the back and goes straight into the neutral junction block (the one with the black tabs). From there, the hot and neutral are fed into the internal outlet box to power the electronics. The hot is also run through the solid state relay on the right and then, together with neutral, to the outlet on the back where I plug in the router.
The solid state relay is then wired up to the Rambo so that marlin can turn the router on and off automatically via M3/M5 commands.
That’s the basic gist of it. I don’t have a schematic handy, or I’d certainly share it. I kinda worked all this out in my head and then methodically hooked everything up, testing as I went.