You have taken a very good look at the roof .. No cuts in membrane ? Checked around all vents and skylights.. Im sure you already know this.. But want to point it out..water flows to point of least resistance.. So the leak can be somewhere else and just flow under the membrane until it finds a opening... Can you reproduce the leak by placing a hose or sprinkler on roof?? You could pressurize that cabinet with a leafy blower or shop vac and get up on the roof with some sudsy car soap...
2010 Georgetown 300FWSSouth Florida