No login prompt via lish on ubuntu 16.04

I usually connect to my linode instance via ssh using a private key, but recently lost this key thanks to a series of backup and hard drive failures.

I thought this wouldn't be a problem, I would just connect using the LISH console. I can log in to the machine via lish, which I can use to shutdown and restart the machine and I can see the machine starting up right up to,

" * Stopping System V runlevel compatibility [ OK ]"

But there is no prompt to enter username and password. The instance runs ubuntu 16.04 LTS which I upgraded from an earlier LTS version of ubuntu about a year ago. Reading online, there appears to be an issue that occurs when upgrading where the login prompt does not appear locally, but having still been logging in via ssh since upgrading I hadn't noticed it until now.

Anyway, if I had physical access to the machine it would be easy enough to debug. I'd try ctrl+alt+F# and see if that gave me a login prompt. Failing that I would just boot into maintenance/single user mode by modifying the usual boot sequence.

However, I can't see how this is possible over lish. Can anyone offer any suggestions?