I am surprised and saddened by all the terrorist conspiracy theorist. Stranger things happen at sea. This was just a bit closer to shore. I doubt we will ever be told what the actual cause was. I can't see a total electrical failure as there are multiple electrical circuits and many generators. All generators would have to "drop off the board" at once.
That being said our second engineer did for some reason stop the maid freshwater cooling pump only to discover it would not self prime on restart. Oops. Mid river with tugs just released.