[knob]

Guggele,
If you can use your player as a memory stick then make sure some music is loaded on, switch on the player and press the play button, Can you still play music on your player?
If you can then you have a chance to get the display back. You need to navigate the menu "blind" to the update option on your player, once you have done this connect the USB and load the firmware and start ConsumerUpdate. Your player must be in update mode for ConsumerUpdate to find the Rock USb device.