By the way, you can skip the Ngon part by chamfering every other vertice on the box after creating it; basically making them into a quad, then adding the additional edgeloops diagonally through those, as in the next step of this tutorial, manually.  Basically, you will end up with triangulated buttons, but it bypasses the Ngon phase.  You will probably need to add more supporting edgeloops to define the buttons later, so it's a little more work.

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