Hello internet people, So, the problem is that my iMac boots on this screen only: I can't seem to boot the OS or Reinstall. Just yesterday I updated my iMac (late 2009) from Snow Leopard to High Sierra. The process was flawless as it should be. When I got High Sierra installed and updated I decided to go for a clean install, and so I backed up my files and held down R+Cmd while restarting. I was not familiar with the process. I did something in Disc Utility, and then I tried to Reinstall High Sierra through the Main Menu but I've been getting the "This disc is locked" message. My only start up option is this which leads me back to the main menu of MacOS Utilities. This is what I see when I open the Disc Utility.. Erasing, Restoring and Unmounting are grayed out in both devices: Is this me or is High Sierra that problematic?