HA not starting after config error

After a configuration change (which obviously has an error) and a reboot of the system (not only restart of HA), HA won’t load anymore. I have a backup, so in worst case I can revert my changes by that, but I’d lose some stats and changes I made before.

Unfortunately, I have not yet set up ssh access by keyfile (I do have the ssh plugin enabled), so I get an error (refused) when trying to ssh into my HA installation. Anything I could do about it? I am not at home right now, so I cannot physically access the device…