HP switch - can't login after firmware upgrade

[MariusKA]

I have a HP 2530-24G (H9776A) switch.
With the previous firmware I did have a manager user with an empty password.
After upgrading to the last firmware YA.16.03.0004 (the one with the new GUI) I cannot login with "manager".

I tried to clear the passwords using the clear button, didn't work, it keeps asking me for password (an empty one won't work).
I tried to reset the switch, same results.

Front panel security is all enabled:

HP-2530-24G> show front-panel-security
Clear Password       - Enabled
  Reset-on-clear      - Disabled
Factory Reset        - Enabled
Password Recovery    - Enabled
Diagnostic Reset     - Enabled
  clear-button       - Enabled
  serial-console     - Enabled

Any help will be appreciated.

Thanks!