Use the Serial Console

The serial console shows the login prompt of the guest and that prompt accepts only a password, so set one now, while SSH still works. A new VM instance has no account password at all, and once SSH is broken it is too late to add one. Security explains why the account starts out locked.

Set a Password

Connect over SSH and set a password for your own account:

$ cubic ssh demo
alice@demo:~$ sudo passwd alice

The command asks for the new password twice. Nothing else is needed, because the account already has passwordless sudo.

Look Up the User Name

The login prompt wants the guest user name. Use cubic show if you are not sure which one the VM instance uses:

$ cubic show demo
[...]
User:         alice
[...]

Open the Console

$ cubic console demo

Log in with the user name and the password you just set. To leave the console press Enter, then ~, then .. The VM instance keeps running.