It is getting confusing: the image in post #15 shows a white wire, not a black one.
@Fractus : help us sort this out:
- How many wires are in that cable from the power supply?
- What are the colors of these cables?
- How did you connect the cables to the micro USB plug?
- If there are more than 2 wires in the cable, have you swapped any of them?
- Which measurements have you made and what were the results?
Please give us a comprehensive and concise explanation. It is hard to follow along when information comes piecewise and partly contradictory.