I´ve tried to update my M13 using my new Mac, OSX 10.8.5.
I used an old Unitor 8 midiinterface and downloaded drivers to make it work with OSX.
I installed a sysexplayer, hooked everything up and followed the instructions.
I pressed play and left it there for a couple of hours.
When I came back it was still in Flash update mode, recieving (I think), so I left it for while longer.
After maybe 6-7 hours I gave up and unplugged everything.
Now every time I power up my M13 I can´t get out of the Flash update-screen.
I took it to the store where I bought it, but they couldn´t help me.
The store contacted the dealer (Luthman Sweden), and Luthman told us I had to change the whole "card".
Is this really necessary?
I have tried to update M13 with my PC before, without any luck (probably because of a crappy-noname midi interface).
But I have always, up till now, been able to go back.