My laptop blackscreens when I connect the power cord, works fine on battery. Why is it doing this?

[Windows Central Question]

My laptop blackscreens when i connect the power cord, works fine on battery.

I upgraded to win10 yesterday. I also see that now that brightness settings are reversed, seriously........I get maximum brightness when I move the slider to the minimum setting, and a dim display when I move it to what should be the maximum brightness setting.