I had the same problem. The display started flickering, then after I switched it off and on again, the display stayed black, although I could still hear incoming notifications. I sent it in for repair. In the repair log, they told me that a cable was replaced. Since I received it back, it has been working without any problems.
The repair was very quick here in Germany. I sent it in on a Monday and received it back the same week on Friday - that's really quick! I could also check the status online.
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