a video is forthcoming but I can't promise when!
Used the power rails ground as the ground reference
Use the sleeve of the patch cable instead, then you don't have to dig inside your case and risk short circuits.
a standard manual yellow volt meter
Not sure I know what you mean by that, have you got a make and model?
We assume you have access to a regular digital multimeter, which shows either resistance, voltage, or current. And set it to DC voltage reading in the 20V range.
not getting any reading
after loading the test patch you should get +5V or -5V when you press and hold one the two buttons, either on the device itself, or using the web page buttons.