To put possible causes to one side for a moment, at what point do they attempt to recover the baggage from the hold (and presumably the cabin)? Obviously it's not a trivial thing to unload, and they won't want to disturb the evidence, but there are presumably pax from the flight stuck away from home with nothing that they weren't carrying in their pockets (although I'd guess that BA will be taking care of them). Obviously if there had been a fire then there probably wouldn't be enough to recover, but it's only been slightly squished in this case.
Has the man with the pot of white paint been to visit yet?