Unfortunately it's not fixable. I am the author of the original thread that started the whole flickergate campaign. I still have my defective surface due to work files and lack of time, I am not able to replace it.
My screen has now pope out of surface as the battery is swollen to almost double the thickness of surface. The diagnosis is that the battery starts swelling which applies pressure on the screen making it defective. I will one day post the complete details on how it starts and what's the end of the issue.
Meanwhile what you can do it is to replace you defective device. MS has extended the warranty on flickering surface pros to 3 years. Contact the support either on twitter or your MS account to start your process.
All the best!