I`ve tried to upgrade the DT25 HD firmware 2.0 through my M-Box 3 (Firewire) MIDI interface. Line 6 Monkey recognized the hardware and linked my DT25. The install progressed to a particular point and then failed during the last stage of the install (800000a error probably with connection). I tried a couple of times and changed my MIDI cables –it still failed at the same point each time. After reading a couple of Forum comments, I decided to try a different interface. Fortunately I have access to a Roland Fantom X7 keyboard which is connected to the computer via USB cable. This worked without any problems which suggest that the problem may be with the Firewire connection. :D
Hope this helps other users who may be experiencing similar problems.