Kemper startup

  • Hi everyone.
    I tried to search a bit on the forum, but I would like to hear your opinion.
    I have a Kemper Rack, suddenly, when turned on, it stops on the Kemper Amp Screen.
    I tried to turn it on with the "booting from Usb" function but at the end of the process it always remains on the same screen. (firmware 7.3.2.)

    - If I try with a too recent firmware, (8.0.6) but it gives me an error.
    - I tried to turn it on by pressing System button, but nothing.
    - Via Usb, the pc sees it but says unknown peripheral.

    Has this happened to anyone? How did you solve?

    Thanks so much