To change the Bios Setting you need an USBkeyboard. Here is the keyboard shortcut list How to enter the Bios and Setup the boot option .

Boot the device and press Delete key enter the Bios.

Chipset

North Bridge Configuration

LVDS Control

Backlight Control –> PWM Normal

Press F10 Yes, Save & Exit. BIOS LVDS Backlight Inverted adjust. If the Windows system brightness controls are reversed, change this option may fixed it.