IBM BladeCenter RAID Battery Backup replacement

Does anybody know if is possible to replace the battery inside of a "IBM BladeCenter RAID Battery Backup Module" (p/n 22R6649) ?
The battery is a double 4.8V 3500mAh (P/N 17P8979) and is easy to find a replacement by many sellers over internet.
CLI output is:

CLI> battery -ctlr 0 -get

Controller 0
Current Machine Local Time: 02/23/2016  02:28:45 PM

  BBU State                                         : 3  (Faulted)
  BBU Fault Code                                    : 10  (Expired)
  BBU Part Number                                   : 22R6649
  BBU Serial Number                                 : xxxxxxx
  BBU FRU Number                                    : 22R6833
  BBU Firmware Revision                             : 58.0
  BBU Expiration Date                               : Sun Jan 27 12:00:00 2013
  Charging state information        
  BBU Charging                                      : False 
  BBU Capacity (Hours)                              : 0

EDIT: I found a possible solution here: https://www.ibm.com/developerworks/community/forums/html/topic?id=77777777-0000-0000-0000-000014928197
They suggest to place the batteries in service status with CLI
mountstate -setobject -dismount -bbu 0
mountstate -setobject -dismount -bbu 1
Then change the batteries and reinstall the first one, wait about two minutes, and check if battery is recognized. The BBU Expiration Date should be reset.
I followed all the procedure suggested (I also powered off the entire Bladecenter) but my BBU is still Faulty and Expired, with the same Expiration Date:
BBU Expiration Date : Sun Jan 27 12:00:00 2013