Black screen with mouse cursor on Mac bootup – Fix

After an Apple Sierra update last night, the 5K Mac that my parents use was stuck at a black screen with just the mouse cursor.  Thanks Apple!

The solution to this I found here:

Keep in mind that you are in a terminal type interface and if on the 5K iMac then the text is readable by ants only.  But it worked for me with some major eyeball focusing.  I could never have expected my folks to do this.

Also, point 3 may take a few seconds to run so do not rush ahead.