Cable
To recap, the amber light means the basestation does not think it’s connected to an instrument, and the green flashing mode key means the instrument does not see EigenD. We also know that power is shared with the data lines so a sketchy cable could lead to this scenario.
The cable had taken a beating on one end and did have some opens, which I fixed. In the meantime, I researched the parts needed to make a new one since it seemed like a good idea to be able to make more.
The instrument cable’s connectors are Neutrik miniCON, using 5 of the 12 available conductors. If you were to make your own cable, I would go with the solder-version complete set (MSCM12) as it has everything and you’ll end up with extra pins for practice. The ones made by Neutrik for Eigenlabs are crimped but the crimp tools and dies are $thousands and have huge lead times.
The cable itself is star quad microphone cable. For the Eigenharp, 4 of the 5 lines (the 5th is grounded to the braided shield) apparently serve as a balanced serial link so star quad is very good for stage applications.
I was not able to identify the cable manufacturer but a good choice for replacement seems to be Canare L-4E6S or Mogami W2534, although I have not yet verified that the cable diameters are compatible with the ferrules that come with the MSCM12.
If you wanted to build your own cable with these parts, using the assembly instructions and pin numbering here, then pin G would be connected to the shield, pins 2&4 would be connected to one of the star quad pairs (e.g. blue), and pins 9&7 would be connected to the other (e.g. white). Supposedly, such a cable would be good to at least 24m.
IMPORTANT: They are not wired like typical star quad XLR microphone cables, where both conductors of each pair color are tinned together. For the Eigenharp each conductor gets its own pin. I’m guessing each pair is a dedicated differential unidirectional serial line, one for send, one for receive.