All brushless esc's have to see a .1500 millisesecond PWM signal on startup or it will lock-out the motor.
Run the switch on the battery + , Transformer + or on the yellow wire of a PC power supply. Dial the servo tester to 20 or 30% travel and see if it calibrates correctly. Mark that spot and return to it every time you startup the system.
Is there some reason you won't run a Tamiya silver can brushed motor with a toggle switch?