The Daily Mail article states that the loaded train stopped at the top of the loop - upside down...
Is that even possible or could that be a SECOND stalling?
Maybe the trims kicked in to try and stop the train making it into the batwing, but didn't quite slow it down enough.
Although in the youtube vid of the aftermath people are saying that it hit at full speed, so who knows?
I think they have got crossed wires and think that when people have said it stopped at the top they meant the top of the loop, but actually they meant top of the lift hill.
I'm sure with all the cameras round the ride for security and for ride ops to see the track Towers should be able to see exactly what happened and hopefully find out why it happened and fix the problems.
But as has been said the main concern right now is the welfare of the passengers involved in the accident.