DTG
Don't know if this will work, try disconnecting the cable for a while, then try restoring the software. You may have to re install the older version first, then install the latest update. If the unit sees the latest update and it is installed improperly, it may not go any further.
If this does not work, get in touch with HB's Support they are great, they will walk you through it and if you do have to return it, everything I have read is that they are very quick on the turn around.
George