Re: If it got interrupted...
First we know everything was slowing down. Maybe they decided they couldn't fix it live and wanted to force a failover.
The Times suggests a big red button was pressed in the data centre by a contractor and the power went down. That might be when BA claimed there was a power failure.
That would be the point when the failover failed. Perhaps that is why the CEO said something about there being millions of messages, although he seems to have stopped saying that now, maybe because it suggests there's something wrong with their IT.
Then I guess they tried to bring the data centre back up, and it looked like the bridge of the Enterprise, shaking about, staff falling to the floor, and smoke everywhere. That would be the power surge.
I wonder how long it was since power and switching to secondary or backup data centres were tested.