RE: Servos fully deflect at switch on
Rebind your radio/reciever with the control surfaces in the neutral position. With trans/reciever on, center your control surfaces. Turn reciever off first, then trans. Control surfaces should still be in the neutral position. Inset bind plug and turn the reciever on. Control surface shold still be in the neutral position. Push bind and turn on the transmitter. Pull the bind plug. Try off then on and see what happens.
Sounds like the servos were moving to a failsafe positon. Even if you did not set one, the initail servo position when you first bind the system becomes the default failsafe positon. ALWAYS rebind before your first flight.
Sherman