I had an issue with my MacBook (latest version) and I tried restarting in recovery mode (cmd+r). The issue is that my password contains a special character (umbreakable space) for security reasons with an alt+Space combination. However the recovery mode does not consider the alt key and the default space is typed instead, therefore the password is incorrect.
Now I’m stuck in recovery mode when booting anyhow with the black screen and a grey lock and I don’t know how to get out of there.
Note that my hard disk is encrypted if that has any impact.