I just recently had a fly-away.... Yesterday in fact. The crystal had worked itself loose and fell out. The reciever stuck where it was, slight left bank, neutral elevator and about 1/4 power. I was lucky enough to retrieve the model. Just an idea.
I know you're pretty bummed out. Just try to learn from what happened and make sure you give your plane a complete check at the start of the flying day. We all probably lack in that area.
Try to be careful when you set up you next plane and look for anything that might cause problems.
Sorry about your plane. Don't give up. After some time, this'll make a great story to tell.... with a little exaggeration of course!