First of all I wrote 1.05 kernel when I wanted to write 1.05 firmware. Sorry for the confusion.
I already applied the 1.05 restore set which matches the firmware version. I did a factory reset after that as well, but without any luck.
I have access to a second PRS-T1 in a clean, unrooted state with 1.05 firmware. What if I copied the partitions one by one to the faulty one? Is the unique information (serial number, etc) only in the 26Mb "unpartitioned space" at the beginning of the drive? If this is so, copying the rest might solve the issue, right?
Do you know what the error messages I posted mean?