This is major issue of samsung g531 cellphone, the screen goes to dark and not show anything on the display.
Customers worried about screen damage but Actually it is not display or lcd fault, it’s only display light issue.
So you don’t worry it’s all ok, Just use this solution and get phone live again, no need any replace the screen or lcd.
Solution: First remove the highlighted resistance then replace the u200 ic, which is also highlighted.
And one other thing which you check, means check the voltage which is already point out in the upper picture solution.
I hope your problem will be solved. All solutions are tested but use at your own risk because company not responsible for any act.