Reset non working cli root password

Hi all

So we've had SCG in for a while and we know the root password, however the system looks to be not working and we can't get to the web UI so I've rebooted the SCG - this came back with the screenshot below.

From here I've tried to login to the CLI using root with the password however this isn't accepting the password that was set, can someone advise of the root password reset procedure please as I can't find this anywhere.