Try the following:
- The headset cannot be turned on while charging the battery. Remove the USB cable and turn on the headset.
- Make sure that the rechargeable battery of the headset is sufficiently charged. If not, charge the headset.
- Reset the headset. If resetting does not work, initialize the headset.
For details about resetting and initializing your headset, refer to the operating instructions supplied with the headset.