Tried to add hack suggested for PiDP10 to add a power keyswitch and USB power connection

ONE OF THE HACKS SUGGESTED IS TO ADD A POWER KEYSWITCH

The holes are already provided on the back panel for a 12mm keyswitch and for a USB-C receptacle for power. The main PCB has a spot to add connectors to wire these up, after which the power comes from the receptacle, switched by the keyswitch, and feeds the Raspberry Pi through the GPIO pins. 

When I removed the USB-C power supply from the RPi and moved it to the new receptacle, nothing happened. No power at all. I grabbed another of the USB-C receptacles I bought, hooked it to a VOM and plugged in my charger. Still nothing.

REALIZATION - USB-C POWER IS A SMART PROCESS

I did a bit of reading and realized that USB-C will negotiate with the device to which it is plugged, agreeing on the voltage required and the current capacity of the USB source, before energizing the power lines. Indeed, it is capable of operating at multiple voltage levels as well as current capacities. 

My charger from the RPi shows that it is capable of delivering 12V, 5V and other voltages at various maximum currents, thus it MUST do the negotiation to figure out what to supply. Sadly, a receptacle with just two wires has no ability to engage in the negotiation. No circuitry exists in the PiDP10 to handle this negotiation either, so the hack is not possible at least not with the USB-C power supply I currently own. 

Perhaps if I can find one that blindly supplies 5V with no interaction needed, it will work, but for now I am unable to use this 'feature' I added. 

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