Can't get past question mark on startup

I am trying to rest the iMac to factory settings and followed the instructions in Support of items to do before you sell your Mac. After the erase disk Step 6, it froze. Now when I try to start it in Recovery Mode on the Internet (cmd,opt, R), all I get is the question mark. I have tried other start up combination to no avail.

Aternatively, I do have a clone on an external drive that starts up fine. Is there any way to recover the MacOS for the internal drive from there?