@Waynet: I'm sorry to hear that you have encountered this issue. Where on the screen is the green line situated, and is it always visible in the same location? Furthermore, is it visible while accessing all apps and features, or in a specific spot such as your Home screen? If is is disappearing and reappearing then this suggests that it is software related, therefore I recommend restarting your phone in Safe Mode, to see if the issue persists? Safe Mode disabled all third party applications, and will help to clarify if the problem is stemming from an external source.
To enter Safe Mode, press and hold the Power button until the 'Power off' prompt appears on the screen then release > Touch and hold Power off until the 'Safe mode' prompt appears then release > To confirm, tap Safe mode.
Monitor the performance for a few hours, depending on how frequently you see the line. If it doesn't appear, then please restart your phone as you would normally, and uninstall any apps you have introduced since you first encountered the issue.
