After experiencing the flicker problem on my surface pro 4 for about 5 months and trying all the posted solutions to no avail. I moved my surface from one room to another requiring me to plug the power pack into a different power source which had no other devices plugged into the same power board, (potential interference problem), and to my surprise, the problem was gone. Its been 4 weeks now and I have not had a single flicker or issue with the screen.
It's one easy step to try but never know it may solve your problem as well. good luck guys.