Traxxas Spartan radio and Swordfish ESC - full speed by itself

[Amisol]

Hello.

Product: Traxxas Spartan
Radio: original TQI (Traxxas)
Esc: Swordfish 220a pro
Batteries: Gens Ace 3s 5000 MAH (x 2)

Have tried the following:

Radio - held the buttons "set" and then "on". Then it starts flashing red.
Boat: Connected batteries and held the button on the reciever. One beep and both units light green.

Then I test the rudder with the radio. Works. Then suddenly begins motor at full speed by itself.
What is the reason?

Thanks for reply!