I got the same issue. Following iFixit guide for removing the battery. It worked normally for 12 hours, then I started noticing issues with touchscreen, then screen turned green and then it went completely black. I took it to official Samsung repair shop. They confimed that screen is dead. Root cause is the same as if it would be liquid spill (but no liquid signs).
I would suggest following Rob's advice: ''It turned out to be adhesive residue from too much alcohol. Also got into the upper microphone and SD card tray. Use alcohol sparingly if you must.''
I would add that don't use any alcohol at all. I also found black reisdues of "melted" plastic on my SIM card.