Here are some things to try first if your Surface Pen won’t write, open apps, or connect to Bluetooth.
Test your pen by inking, writing, or erasing in OneNote, Sticky Notes, or Fresh Paint. If your pen works in one of these apps, then the app you want to use may not work with pen.
Open apps and use your Surface with touch. If you can't use your finger on your Surface, go to Surface touchscreen: Problems with touch. After touch is working, try your pen again.
Check the battery level of your pen. If you've paired your pen you can check this in your settings. Go to Start > Settings > Devices > Bluetooth & other devices , then find your pen to see the battery level. If the battery is low or doesn't have power, you may need to change or charge your battery. For more info, go to Change Surface Pen batteries.
Check your pen settings. To check your cursor, handwriting, and top button settings, go to Start > Settings > Devices > Pen & Windows Ink . To check your pen pressure settings, open the Surface app and select the Pen tab to adjust it.
Check the LED light on your pen. If you aren't sure what the LED light on your pen means, go to the section My pen won't pair with my Surface or The light on my pen is blinking red or doesn't turn on.
Run the Surface Diagnostic Toolkit.