so an old version then, try updating it.
Did version update V100R001C206B026, however, the default password and the super duper admin password not working now ('@' plus the last 8 digits of my serial number)
Also, following the instructions, admin and admin did not work.
Yup, followed those VF instructions, still did not work for me. In the end, I did a 10-second hard reset and I was able to get to factory default. Then I restored my configuration from my backup, and then I was able to log in as normal.