Okay just found what I think is the transfer switch but it appears that it has a small water leak going into it.
When I try to take the cover off with everything shutdown I got some water leaking into my hands. There was a paper towel sitting there and it's socked. Since the rear toilet and sink are directly above it (genius design) I think it's one of them.
Can't figure out how to take the cove off to take a closer look, but I see a couple of screws so I will try it out.