I am interested in why the booms feathered prematurely, but I expect there was a simple cause and the solution will also be relatively simple.
More interesting is why the craft broke up. I think that is also relatively simple - the booms deployed while the motor was running. This would cause the centre of resistance to be way above the thrust line. i.e. the forces would cause the craft to tumble violently. At mach 1, no craft could stay together.
Looks like an interlock is needed, or that there was an interlock but failed.