Why root is not known through Lish ?

Hello,

I am having a trouble to get into my Linode, after upgrade. SSH returns:

port 22 : connection refused.

So I tried Weblish. But when I enter root as login, it returns:

login incorrect

I changed root password from Cloud Manager, but I have the same issue. It is not a problem of password since I am stuck at the login step.

The same issue is pointed out in the following thread but no satisfying answers have been given : https://www.linode.com/community/questions/22419/how-use-login-in-lish

Could someone help me?
Regards,