Nokia BH-109 hard reset

To repair and reset your Nokia BH-109 :

Plug the charger into a wall outlet, and while you press and hold the power key, connect the headset to the charger. Use one of the following chargers: AC-3, AC-4, AC-5, AC-8, DC-4, or DC-9.

Cannot connect the headset to a compatible device? Make sure the headset is charged, switched on, and paired with the device.

Nokia BH-109 pairing

1 Switch the headset off and the compatible device on.
2 If you have never paired the headset with a device, or you have emptied the paired
devices list, switch the headset on. If you have previously paired your headset with
another device, press and hold the power key for 5 seconds. The headset enters
pairing mode, and the green indicator light starts to flash quickly.
3 Within 3 minutes, activate Bluetooth on the device, and set it to search for Bluetooth
devices. For details, see the user guide of the device.
4 Select the headset from the list of found devices.
5 If required, enter the BH-109 passcode 0000.

You can pair your headset with 8 compatible devices, but you can only connect it to a maximum of 2 devices at the same time.