I installed Windows 10 Pro on my L521X last night and the brightness controls worked UNTIL the system updated. I figured it was just a simple display driver issue, so I figured that the Windows 10 drivers from Dell would fix it. They didn't. I tried using the device manager to update the drivers for the video card and display, but they are already up to date. I tried to roll them back, but there's nothing to roll back to. Any way I can get back to a working state? TIA
I am using l521x too. We must wait for update driver from dell or you can change bios settings. Secure boot - disable, legacy boot - Enable. You can change brightness. But your device not show Dell logo when boot.