RE: What Happened???????????
If moving the receiver antenna, or touching it, causes problems, we'd say that the receiver should be looked at. Just changing the switch should not be so dramatic. If the switch is bad, you'd either get operation or no operation when the engine's not running. When the engine is running, then we'd expect glitching because the power would be flickering on and off.
If you perform bench tests and field range tests with the model's engine running and not running, and are satisfied with how the system performs, then you may want to try flying it in a "more expendable" model. If you get good flight tests, you can then decide if you want to trust the system.
Otherwise, we'd be glad to check it out for you.