I am no expert on this problem, I had the same problem.
This how I fixed it, it might not work for you but give it a go.
1.) Started DBox II - Bootmanager.
2.) select correct com port.
3.) select the image you wish to upload (Utilities -> image Flashen)
4.) unplug the dbox (leave for 20 seconds)
5.) Press Start on Settings then Plug in Dbox again.
The first upload took about 15 minutes, the progess is shown in COM-terminal.
when it is finished you have to unplug the dbox , when I plugged mine again it was back up and running.