I did not manage to send it in yet. Opening hours of the bloody post office and my working hours did not fit together. Going to send it off tomorrow. Keep you updated.
Just FTR, did you do anything special before the behaviour started? My phone did not drop lately (it has dropped before), and the only thing I changed during the last days before the screen stopped working properly was to encrypt it, again.
This surely does not cause the display to fail, does it??