Originally Posted by BrianG

Dunno about paragraph 1, but your "update" sounds like the BEC in the MMM is toast and the only way it will work is to externally back-feed 6v into the MMM. When you do this, does the rx pack/regulator get hot, and/or does the BEC circuit on the MMM get hot (you'll have to take it out of the case)? Depending on the MMM BEC circuit design, putting a voltage into its output can cause lots of heat. To me it sounds like your MMM evolved into a form of Opto-ESC.

I would send it back since that is obviously not how it is supposed to work. Good luck and let us know how it turns out.