RE: Help TURNIGY 80A beeping question
The tone is actually coming from the motor. Look up "voice coil" on wikipedia for more information on how this works.
When the tones sound depends on the ESC design. Some ESCs only beep when they arm, some beep a certain number of times when they're powered up, and then beep again when they receive a signal from the receiver to indicate that they're armed.
I'm guessing that the motor no longer responds to the throttle? First thing to do is double-check all the connections.