Same issue with my 400.Tried the different port and cable fix (three cables, two PC's and a laptop which means however many tries you can do with three cables 9 ports) and still not recognized,still stuck on "v1/31 please wait..."on startup. Tech support says take it in, which I'm guessing will cost more than the 120 bucks these things go for used.
--Anyone have any success connecting with a midi to usb cable?
--Is there some sort of global reset (not the factory preset thing) on the HD400?
All this just to get the plexi modelin 2.01...sigh