Tried upgrading from 02.11.07 to 02.28.00

Anyone knows where I could find some more info about the "static EEP backup" besides this wiki X-Gold_608 ?

BBUpdaterExtreme queryversion is giving me this:

Checking static EEP backup...
- backup is not sane. Recovery needed
Checking static EEP backup -- All OK
Device IMEI: 004999010640000
Firmware version:ICE2-02.11.07
EEP Version: EEP_VERSION:526
EEP Revision: EEP_REVISION:0
Boot Loader Version: ICE2_BOOT_05.09_G2M3S2
FLS/EEP Mismatch: Match
Re-enabling ...

and ./BBUpdaterExtreme update -f ICE2_02.28.00.fls -e ICE2_02.28.00.eep
Has the following error:

!!! Exception at :0: - kBBUReturnFlashError(18)/17: Can't update. Static EEP appears to have problems

Thank you