Download the Lenovo Power Management Driver or Lenovo ACPI Driver directly from the official support site.
The ACPI (Advanced Configuration and Power Interface) acts as the bridge between your OS and BIOS. If the BIOS is outdated, it may not correctly report the FNBT0000 device. acpi fnbt0000 driver fix
In Device Manager , right-click the "Unknown Device," select Update driver , and choose Search automatically . If that fails, download the driver from the manufacturer and use Browse my computer for drivers . 2. Update System BIOS/UEFI Download the Lenovo Power Management Driver or Lenovo