try root as username and your password from the NGCP user.
I'm trying with root user; I can access from virtual console, but by ssh (I already change the root password to test).
From the GUI, you should be able to edit the sshd_config file under Configuration > File Editor, then select the appliance you need to get into.
Inside the file you should see a line that says "PermitRootLogin no" or perhaps a commented outline saying "#PermitRootLogin yes".
Make sure you have an uncommented line saying "PermitRootLogin yes".
leone this is for MWG not SIEM