Hey Dmitri!
Just got my MegaDrum, and it has a FW from 2011.
I believe I have AT644 board. I know I am limited with future updates, but I can not find a way to update to the newest firmware.
I am running OSX 10.11.6.
I have the megadrum644_48_20160529 FW downloaded.
I have downloaded both, Mega Drum Manager, and mdfwupdate
Attached are the screens that I believe are relevant.
I have tried setting my MIDI to be the same port, and different ports, 1 and 2.