How do I start Apple Diagnostics?
How do I start Apple Diagnostics on my macbook pro 15.4 (A1398-Mid2015 Model). I tried holding down the "D" and/or "Option-D" when booting up and Apple diagnostics does not start up.
[Re-Titled by Moderator]
How to use Apple Diagnostics on your Mac
Do you have a firmware password enabled? If so, turn it off. See link at the bottom of the above-linked article.