I recall an old article about these batteries (https://electrek.co/2016/12/19/tesla-fire-powerpack-test-saf...) in which testing showed that a failure within the battery itself would be contained by the cooling system, but a failure outside it wouldn't. Since the fire in the pictures on this article doesn't look contained, I wonder whether the cooling system was turned off at that moment (because it was not yet in operation, or because it was turned off after the failure started), or whether the fire started outside the battery modules (for instance, in the wiring).