Aut cum scuto aut in scuto
Looks like it vacuumed?
That's why they test it...
Perhaps a test procedure failure? They were filling the lower O2 tank when they found a valve issue. So they stopped and started filling the Methane thank on top. With the O2 tank empty it may not have had the structural integrity to support the weight of the filling Methane tank and the structure collapsed in the area the empty O2 tank was located. Just a guess.
looking at the structural design, I agree.
NASA is saying "Hold my beer"....