Hi 김혜림3,
Welcome to Microsoft Community.
It sounds like your Surface Pro 9 is having intermittent issues recognizing the Surface Pro Signature Keyboard, and this could be related to the firmware or drivers. Here are a few steps you can take to resolve the connection
recognition and backlight issues:
- Update Drivers and Firmware: Make sure your Surface Pro and keyboard drivers and firmware are up to date. You can use the Surface app to check for updates. Open the Surface app, go to Help & Support, and select Check for updates.
- Reset Surface Pro Type Cover Connection:
- Detach the Type Cover from your Surface Pro 9.
- Clean the magnetic connectors with a microfiber cloth to remove any dust or debris.
- Reattach the keyboard and check if it is recognized immediately and if the backlight starts working.
- Run the Surface Diagnostic Toolkit: Fix common Surface problems using the Surface app and Surface Diagnostic Toolkit - Microsoft Support
- Manually update Surface drivers and firmware: Download drivers and firmware for Surface - Microsoft Support
- If none of the above steps resolve the issue, reset or refresh Surface may be necessary. This can help if there are any corrupted system files causing the driver or keyboard recognition issue. Ensure you back up any important data before performing this step. Restore or reset Surface for Windows - Microsoft Support
I hope this helps. If there is anything not clear, please do not hesitate to let me know.
Your Sincerely
Hahn. W - MSFT | Microsoft Community Support Specialist