If it can be useful I still don't see the u-disk.
I tryed with the s1fwx tool and I got:
s1fwx v2.6 - copyright (c) 2005 wiRe (
http://www.s1mp3.de/)
repair dumped firmware file...
backup file to 'dump.bi$'...
try to repair firmware...
error: repairing file failed