I got it working! I was able to run power via the battery port. According to the instructions, I had to solder a jumper #4 closed; turns out there are two #4 jumpers… I no longer have the strange theramin action whereby the scope is only working when my hand is near the panel; it is now working all the time.
I found out I still need to do some checking of the scope kit, as the displayed signal seems upside down… 
0V and ground aren’t necessarily the same thing. 0V is the reference for the power of a project, PCB or circuit. Ground is the safety connection most modern PSU’s have that is actually connected to the grounded mains socket. These are internally connected in a lot of simple devices as most modular synth modules are. But in more complex or sensitive designs you can have multiple 0V reference points, you see this more in analog/digital hybrid designs.
In most cases (all that I have seen) these 0V reference points meet up at the PSU but connecting them randomly to a 0V reference point can make the circuit unstable or inject noise.