[Gustav]

Leaving the jumper on shouldn't smoke the controller just like that,in fact don't they suggest using both together in certain circumstances?

I wouldn't use the internal BEC on a MT,it's more a convenience feature for low cell counts,it creates more heat,which needs to be dissipated so the controller is more efficient when you don't use it.It doesn't sound to me like you did much wrong at all,remove the black jumper if you're using a rx pack or ubec though.