Elen, have you tried seeing if any screen sessions exist at all?
screen -ls
-should list all screens for the current user, or you could try:
ls -laR /var/run/screen/
-to show all screens on the system.
And if you find a screen you could use:
screen -x screenname
It might not be running in a screen session, I know the Chinese Dragon miners don't, it could just be a nohup session or even as a background process at boot time in rc.local