[OpenAFS] - Locked volumes

[ProbaNet]

Hello!
	We have a locked volume and we are unable to unlock it (it's an
important one, it stores a big list of dirs / mountpoints for other
volumes). It has been locked during a release operation which is now
aborted due to a failure. We tried:
- vos unlock vol -verbose [CTRL+C after 20+ minutes]
- vos unlockvldb -verbose [CTRL+C after 20+ minutes]
Both commands failed (they wait forever with no output). The logs seems
to be "ok" (no errors in VLLog / VolserLog / etc..). We have the quorum
(checked with udebug) and all seems to be fine.
Here's the bad volume:
-----
vos examine vol -extended -verbose
Fetching VLDB entry for 536883527 .. done
Getting volume listing from the server afsmn1.xxx .. done
vol                               536883527 RW      30921 K used 26887
files On-line
    afsmn1.xxx /vicepa 
    RWrite  536883527 ROnly          0 Backup          0 
    MaxQuota          0 K 
    Creation    Wed Oct 26 10:55:15 2011
    Copy        Wed Jan 25 16:38:36 2012
    Backup      Never
    Last Access Mon Mar  5 15:54:55 2012
    Last Update Mon Mar  5 15:54:55 2012
    0 accesses in the past day (i.e., vnode references)

                      Raw Read/Write Stats
          |-------------------------------------------|
          |    Same Network     |    Diff Network     |
          |----------|----------|----------|----------|
          |  Total   |   Auth   |   Total  |   Auth   |
          |----------|----------|----------|----------|
Reads     |        0 |        0 |        0 |        0 |
Writes    |        0 |        0 |        0 |        0 |
          |-------------------------------------------|

                   Writes Affecting Authorship
          |-------------------------------------------|
          |   File Authorship   | Directory Authorship|
          |----------|----------|----------|----------|
          |   Same   |   Diff   |    Same  |   Diff   |
          |----------|----------|----------|----------|
0-60 sec  |        0 |        0 |        0 |        0 |
1-10 min  |        0 |        0 |        0 |        0 |
10min-1hr |        0 |        0 |        0 |        0 |
1hr-1day  |        0 |        0 |        0 |        0 |
1day-1wk  |        0 |        0 |        0 |        0 |
> 1wk     |        0 |        0 |        0 |        0 |
          |-------------------------------------------|

    RWrite: 536883527     ROnly: 536883528     RClone: 536883528 
    number of sites -> 8
       server afsmn5.xxx partition /vicepa RO Site  -- Old release
       server afsmn1.xxx partition /vicepa RO Site  -- New release
       server afsor1.xxx partition /vicepa RO Site  -- Old release
       server afsmn2.xxx partition /vicepa RO Site  -- Old release
       server afsmn3.xxx partition /vicepa RO Site  -- Old release
       server afsrm1.xxx partition /vicepa RO Site  -- Old release
       server afsmn1.xxx partition /vicepa RW Site  -- New release
       server afsmn4.xxx partition /vicepa RO Site  -- Old release
    Volume is currently LOCKED
-----

Any suggestion? :) Thanks for your help!

Stefano
Fabio