I had my Dell U2713H 9 months ago. Recently I've noticed flickering with horizontal lines (which is my main problem) which appears once every 3-5 mins. Anyway I searched for a solution and found the perform Built-in Diagnostics in the manuals. So I tried to do it but when I came to step 3. Press and hold 1 and button 4... nothing appears and the floating box keeps moving around.
When I turn on the PC and open the menu I can press all buttons normally. Please advise why I can't do that and what could cause the flickering issue. And does the Built-in Diagnostics fixes the problem?