Hi, I'm lost, I wanted to reset my MacBook Pro retina back to factory reset. However, when I erased the startup disk I did not back up anything because I did not have anything valuble to save. Now, when I try to reinstall macOS Sierra I am unable to select the "OS X Base System" HD. It's says "this disk is locked," and I'm unable to install it. Is there anything that I can do to fix this issue?