When you are setting the eufyCam up, there should be a beep sound if you press the SYNC button. This is the Device Setup Guide: Setting Up S330/S300 eufyCam (eufyCam 3/3C) in the eufy App 

If there is no beep sound when you press the SYNC button, please try the following tips to see if the issue can be fixed.

Fully charge the camera

Please refer to this article about how to charge the camera: How to Charge eufyCam  

Press the SYNC button harder

 Pressing the SYNC button, you are supposed to feel the click of the button. If not, it means that you are pressing the button a bit too loosely and it doesn't work.

Press and hold the SYNC button for at least 2 seconds 

If the SYNC button isn't pressed and held for enough time, it will also fail to emit the beep sound.

Factory reset the camera

You can also try to factory reset the camera by pressing the SYNC button for 10 seconds.

If there is still no beep sound after trying the troubleshooting above, please contact us for further assistance.