of course i plugged in a 1/4 " cable in order to turn the guitar on. well the factory reset (as described in the manual) didn't work either. a line 6 employee told me that it is not possible anymore for the jtv-89f i got (>wtf line6?)
well but i found the solution to the reinstallation problem with the flash memory. I put the usb interface from the varaix into a usb hub and not the usb port directly (again > WTF LINE 6???).
so my advice for everybody having issues with the line 6 monkey and updating >>> try other usb ports ;)
supertonic_jack's post in Help! Cannot Reinstall JTV Flash memory was marked as the answer