If the chance of a catastrophic event happening is one-in-a-million, then it is equally likely to happen on the 13th and on the millionth coin toss.
> Assuming that the normal rate of battery fires after collisions is one per million, the probability of observing such a fire after only 13 collisions is rather low.
What you're arguing is that the probability of it happening on or before the 13th time is less than it happening on or before the millionth time -- Which is self-evidently true of _any_ probability, and is a much weaker argument.
> perhaps the rate is not one per million
This is much closer to the argument you should be making. I.e. "Given that a purported one-in-a-million event occurred after only the 13th test, what is the probability that their estimate of one-in-a-million is accurate?"
(I don't know the math to answer that question, but I hope somebody that does will come along and chime in.)