What is the servo to the right of the steerage servo? something to do with carp delivery?
Pretty standard to check all contacts, i.e. chocolate boxes. Also try different receiver ports, as often these may fail.
With the ESC, is there not any specific programming functions, (i.e. hold a certain button for x seconds)? i suspect that like you said, there is a wiring problem with the ESC, as the motor works when you hardwire it.
hope this helps, as this is all i can see!
Dan