Holding down the power button would get my old MacBook to boot when it was stuck in the shutdown during boot behavior, but I'd still eventually suffer a sudden shutdown later. Thank heavens I didn't have any lost work or severe drive corruption.
I'm wondering about running yes to heat stress my replacement MacBook, but I'm afraid to do that and possibly make this one unstable. On the other hand, the hardware should be able to handle full CPU load without suffering. Without knowing the exact cause of the random shutdown problem, I have no means of estimating whether or not "yes" would induce an issue. Eventually, I'll stress it, but for the time being I'd like to enjoy a few days of using the machine. Might be solid anyways, but I do hate this heightened sense of distrust of my laptop. I rely on mine everyday as my main machine. It does major duty all day running from operating room to operating room.