Hello, Some time ago I brought my mid-2014 13" MBP to an Apple Store for a repair, and I saw the guy at the Genius Bar check its hardware by holding some key (combination) at the startup of the machine. I were thinking that it was just the Apple Diagnostics (or Apple Hardware Test for older MacBooks). But recently when I tried to start up the machine to Apple Diagnostics (by holding the D key), I realized that it is not the same (the interface is not the same). I checked all the start up keyboard combinations here: https://support.apple.com/en-us/HT201255 but it seems that none of them has that function. Does anybody have any idea about that? (Would be useful for those who buy second-hand machines ) Thanks in advance!