Thank you. I finally figured it out last night after watching another dozen videos, Some of them were just flatly wrong and some were so out of focus that it was hard to tell what was going on. What I could finally see was that there are three modules in the box and the people filming them could make it immediately understandable by saying this unit is closest to the engine. This unit is in the middle of the box and this one is nearest to the battery

Thank you.