Downgrading C5683A firmware

[Denis Mante]

Hello all,
I own a C5683A Surestore for years, and saved data on many tapes using systematic hardware compression.
It was using the C111 firmware version, and worked fine.
I once launched LTT, which told me that C305 firmware was the latest firmware.
Confident, I upgraded my firmware to C305.
Til then, seems that I cannot read all my backups, NtBackup says all tapes are "unrecognizable media", and asks me if I want to format them.
Seems to me that the new firmware hardware compression has changed.
Now I want to downgrade to C111, to read my tapes again because they contain valuable media .
LTT tells me that I need a password to downgrade. What's that password ?
What can I do to get my tapes readable like before ??
Thank you HP if you can help me !
Denis.

[MWills]

I recommend you to call HP Support Center. If you are in US and Canada call +1 800 633 3600 and follow the IVR. If in other country then you can find you local HP Support Phone Center number at http://hp.com

You may email the LTT support team for help too: ltt_team@hp.com

[Denis Mante]

Thn'ku Marcial (at least for the LTT team email).
I've opened a ticket at the Tape&Libraries support.
Seems that the password they give you is kinda time limited, so looks like I can't get it from elsewhere than HP.