I came across some hindrances when moving from the "Proof of Concept" to "Prototype" stage.
Or better said, from the “plastic case” to an “aluminum case” stage.
Aluminum is a conductor, plastic is not.
Consequently, well, you get it.
Oh, and by the way, the 5-pin DIN connector, when used for a factory powered chair/recliner/bed (and unlike its shared MIDI use), the case is very-much used. If you read any of my previous logs, in hindsight this is precisely why I fried my original Raspberry PI.
Why didn't I learn?