From page 34 of the NTSB report, this gem.
During this incident, the supply valves (which are electrically driven) lost electrical power after the APU shut down because the APU was the only source of electrical power being used at the time. As a result, smoke generated by the APU battery could not be effectively redirected outside the cabin and aft E/E bay.
I am sure lots of professionals on this forum will now step forward to explain that this is no problem.
I think before the 787 is let loose again, a test flight might be made with the families of some of the executives on board.