I have a Mac Mini 2010 server model running El Captain. I bought it used and it already came with El Captain installed on it. I would like to run a diagnostic test on it. Unfortunately, when I invoke OPT+D and I wait for Internet Recovery….it comes back saying “AHT does not support this machine”. I am not able to run diagnostics the typical way by pressing D on the keyboard. When I try that the screen is white/grey and eventually it boots normally.
I am guessing Internet Recovery is newer than the machine therefore I can’t run it. I could use the original DVD and install a fresh copy of Snow Leopard then try and run diagnostics after a successful installation.