I was in the FBW Development version, in climb mode when the autopilot kicked out, the plane went into a dive and throttled back. I tried to go to manual speed by canceling autothrust and and pulling the speed knob but nothing would recover it. I checked the program was in DES mode and could not get it back to cruise of climb. In real life there must be a way to restart a climb or select any mode. However, it seem in the FBW whenever the you start down, you’re stuck in DES mode. BTW, I may have iced up but I didn’t think I had icing turned on. Anyway, I flew the route again and had a perfect landing in kbna. Thanks for your replies and interest.