Just a point. I'm a Boeing pilot and I'm not familiar with Airbus systems.
In the case of an electrical failure, there should be a systematic shut down of systems-ie non essential items first. Would ACARS fall into the bracket of a non essential item? Would the fact that it kept transmitting faults until a final catastrophic conclusion to the events(as indicated by the cabin v/s message) indicate a random shutdown of systems in a progressively deteriorating situation? Also there has been a suggestion that the on board mobile phone system continued to operate.
To me there is only one thing that could cause a shutdown that would leave non essential items operating while essential items such as the ADIRU's and ISIS shut down and that would be a fire in the avionics bay knocking out essential systems in an erratic manner and not shutting down non essientials first.
Whether the fire was caused by a lightning strike is another matter.
For the record I spent the evening yesterday with the family of a beautiful girl lost in this tragedy and am merely trying to better understand events.