My (old) iPhone 4S has some issues with its screen. There is no water damage and the issues started on its own, I did not drop the phone. This leads me to believe that simply one component failed, I'm not sure whether it's the logic board or the screen itself. The (constant) symptoms are basically as follows:

1. Contrast -he screen has noticeably less contrast than it should. Everything appears "lighter" than it should.
2. Flickering - the screen flickers noticeably. The visibility of the flickering depends on what's being displayed, but there's definite constant flickering.
3. Horizontal lines - if there is for example white text on a darker background, the background left and right of the text will appear lighter. It kind of looks like two beams of light exactly the height of the characters are being emitted from the writing.

Does anybody have any experience with this and/or can tell me whether it's a screen or logic board issue?