After which I tried to switch off the remote, then the heli went crazy! Its rotor blades seem to be at full throttle and starts spinning out of control.
You can't turn your remote (transmitter) off before you turn your dragonfly (receiver)off. You have to turn your receiver off first or your dragonfly will go crazy. As for your servos making strange sounds, are they digital servos? Digital servos will make a strange buzzing sound.
Can someone tell me anything about the servo reverser function on the remote and what exactly does it do. Could it got to do with it?
You can reverse the direction in which your servo travels (left to right or right to left). You have to make sure that your servos are going in the right direction or you will have a big problem when you try to fly your dragonfly.