Others have experienced this same issue, but there has been no definitive answer as of yet so we really don’t know where the defect is. Personally I would contact Apple, get to a senior advisor to try to find out exactly where the issue is emanating from before buying any parts.
https://discussions.apple.com/thread/7041843
Your issue seems to be this one:
https://www.youtube.com/watch?v=vM8pJb-ZqLA&feature=youtu.be