It is rare but NOT impossible to be shot down due to radio interference on 2.4ghz. It has happened at the local fields in this area but the are considerably rare. If you have thoroughly inspected the control surfaces, linkage, load tested the battery, checked every servo wire for damage, and rang checked the radio, eliminating everything else, a radio shoot down is the only cause I can think of. I would still ask around at the field to see if any other incidents have been reported.