Linkstation Pro Duo - LS-WTGL/R1 US, continuous array rebuild - how to stop?

[wfuson]

System:  LS Pro Duo LS-WGTL, F/W:  1.09, 2xWD 500GB RE / Black disks

Problem:  I attempted to erase the array using the maintenance menus.  The system has been rebuilding the array (flashing "i" 1 - 6) for 9 days running continuously - and shows no sign of coming to completion.

NAS Navigator does not recognize the device and I am not able to log in using a browser.  It is non-responsive.

Questions:
     a) is it normal for the unit to take this long to rebuild the array?

     b) if not, how can I recover the unit.

Environment:
I'm still using a couple of TeraStations and another LS Pro Duo for backup purposes - so data loss is a non-issue.   All the data is backed up either on another NAS device or in offline backups.  FYI, the other Pro Duo is at a higher F/W level that is apparently not compatible with "failing" unit, so I don't know if I can use a formatted drive from the working unit to help recover.

History:
The unit had no operational problems, I was simply trying to clean the disks prior to using it for another purpose.  The WD drives were put in due to reported disk errors a few years ago.   The configuration was a single array, RAID 1, approximately 35% of capacity used.