[frolinmod]

I opened mine up when I first got it. I wanted to replace the stock USB cable with a different one. My MHP is the same basic design as yours, but the details differ a bit. One difference is that the USB cable on mine is not soldered to the board. It's a regular USB A to B cable and there's a USB B socket inside that it plugs into. That made substituting a different cable trivial. The extra unused internal port in mine also has an actual pluggable port inside. I don't remember if it was mini-b or micro-b. I don't think it was A. I'd have to open it up again to check.

I presume you have some peripherals that are USB powered and want to be able to power them up and down remotely. I suppose you could use one of the switched power ports on the MHP to power a 12V relay whose relay contacts would make/break the +5V line on a corresponding USB port.