X1C Windows Screen Brightness

[harry62]

X1 Carbon 6th generation (refurbished just purchased) has screen brightness only 50% of my P50 and iPads. Many similar complaints found online; problem perhaps due to auto brightness gone amok. Tried but cannot find the option to turn off or toggle the auto feature. Where is it hidden? Latest Lenovo and Windows updates and drivers installed. I see various different suggested ways to get to the magic brightness control but it is not there.

I called Lenovo and they told me I have warranty for hardware problems for a year BUT fixing a software issue costs flat rate of $169 for a year.