Peter We
The battery box is not a fix or solution to the problem according to the FAA
The JAL Boston and ANA Takamatsu incidents highlighted 2 issues:
1. The battery failure rate (thermal runaway) was considerably higher than expected.
2. The original battery box did not contain the fire which it is supposed to do in the rare instance that there is a battery failure. Special rulings were issued by the FAA during the 787 delvelopment on this. Sorry I have no time to go back through this thread to find this data.
The battery modifications such as the extra insulation between cells addresses issue 1. The stronger box addresses issue 2.