I have the same problem. I tried extract ftf firmware, and flashing it with fastboot with command "fastboot flash userdata userdata.sin". I just get information on non existing userdata partition.
I can't wipe dalvik or factory reset, because userdata don't exist. I can install rom in recovery, but it just loops on android logo.
What can i try? i already flashed 4 different stock firmwares.
ok, just use older flashtool. Newest will just brick your phone. Use 0.9.18.4 or older.