1. Remove the propeller for safety.
2. Make sure the esc is plugged into the throttle channel.
3. Make sure throttle stick is low AND trim is also low to ensure you have at least -100%.
4. Try re-binding to see if this now work.
5. If not, try moving the throttle stick to full once you hear the beeps to see if this makes any difference to the tones you hear. If the tones change, pull the throttle stick back to low and see if it is now binding OK.
6. Try binding the receiver using a different esc to establish that the receiver is working.