Hi, I got a used 2013 iMac, (thin one with no CD drive) I keep getting this white screen with flashing grey folder with "?" in it. I've tried holding down the COMMAND button, nothing happens. I've tried holding down the OPTION button during start-up and then I get a grey padlock with a blank password and dark grey circle button next to it. What is going on or what am I doing wrong?
Thanks!
Thanks!