Firstly, IF and it is a big IF, the fire started in the dangerous goods then if my memory serves me correctly then all the DGR should be loaded in an accessible and visible position, this means no DGR on the lower decks and none in sealed ULD’s .
Wrong , only CAO has to be accesible and DGR can go in sealed ULD's and anywhere on the aircarft . The only rule is to have it in the front of the uld and to the right side so its easy to find , Also DGR can go in the lower deck positions
Bigbore