While looking for Steptoe's original post on ADVRIDER stating he could fix some of the ABS units I found this recent thread where he did reveal how it can be done. See post #11.
If this doesn't work you may want to PM him and see if he thinks your unit is fixable.
Another option is to call these guys Although they rebuild BMW car ABS modules they may not want to do a motorcycle; however, my guess is if you get the right person he/she may be able to tell you what the likely issue is with your unit and how it can be fixed. What blows me away is they give a better warranty on their rebuilds than BMW gives on the OEM unit.