Lenovo Pen Software
To use the Lenovo pen, first ensure you've downloaded the software from the Microsoft App store. When you install the software, ensure that the pen is inside the laptop.
When you start the app look for the option to show battery percent and turn on. Then remove the pen from the laptop and go the taskbar on the right side and look for a battery icon that is standing (pointing) up; hover over it with the pen and icon should turn green and display a percentage.