If you are hearing the startup melody (you can unplug and replug to verify that is the same sound you are hearing) that only occurs on startup
You can see it in the code here https://github.com/OpenGarage/OpenGarage-Firmware/blob/master/OpenGarage/OpenGarage.cpp see play_startup_tune();
The only other sounds are the closing automatically beeps which are different
It actually happens before Wifi connection occurs but that would only be a second or so behind.
The other thing this could be is your power supply – ESP devices (the wifi chip inside) can do that if they can’t pull enough current. If its easy to swap out that would be a good test… if all else fails you will need to connect it to a PC to see what it output when this happens.