I believe that the drip trays located in the fwd MEC failed ( maybe the trays were missing altogether) this should have prevented any water leaking this time from the First Class galley from getting into the electrical system.
Some of the components on those rack are many of the Control units including the Generators Control Units GCUs that would have tripped off line
Boeing believe that there was no requirements for the 400 to be started a APU in flight.
Unlike the B747 classic which some had in-flight start capabilities these had a special air scoop fitted on the APU door,