To pair your Surface Pen with your Microsoft Surface device, follow these steps:
1. Go to Start, and select Settings > Devices > Bluetooth.
2. Turn Bluetooth on.
3. If Surface Pen appears in the list of discovered devices, it may not be properly paired yet. So, select it from the list and remove the device.
4. Press and hold the top button of your pen for 5-7 seconds until the LED flashes white to turn on Bluetooth pairing mode.
5. Select your pen to pair it to your Surface.
