my Mac Pro heated quite a lot last night and wouldn't start . Just started.how do I run wireless diagnostics

To test everything, run Apple diagnostics as described in your linked article.

To run only wireless diagnostics (which does not test the rest of your system) Hold down the option key while clicking on the Wi-Fi Icon on the MenuBar to reveal a drop-down menu on which wireless diagnostics is a choice.

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what model Mac Pro, by year, early mid late, and processor speed?

or is this a MacBook Pro, what model by year, early mid late, and processor speed AND what screen size?