If your DuoSense Pen Stylus no longer responds when interacting with the touchscreen, try the following steps in order to reset the stylus:
1.) Open the pen battery cap and remove the cap entirely from the rest of the pen.
2.) Wait at least 10 seconds.
3.) Screw the pen battery cap back into place, without stopping, until tightly closed.
4.) Verify that the pen is now functioning.
If the preceding steps do not resolve the issue, follow the link below to setup an RMA: