Agreed, but to get a short circuit, you need current flow from one terminal
of the battery to the other. Even if one side were grounded before the fuse,
the other side would still be floating, so no current flow.
Sorry, I should have been clearer. The return path is through the damaged battery casing via the ELT casing.
The first announcement we had was that the battery seems to have sustained pre-fire damage and the crushed wire finding came later. Is that still the case?
My statement above was based on a scenario where the crushed wire, from the time of assembly, was a passive and isolated path to the casing until such time as the cell burst and exposed the anode or cathode to the ELT casing. If the crushed wire was the opposite polarity to the part of the battery that had become exposed then, current will flow.
This, of course, assumes that the battery did rupture at some point. As you correctly point out, a crushed wire itself, will not complete the circuit.