Black Screen MZD

Hello,

today i wanted to install the v70. I pressed the Start-Stopp Button one time and successfully installed the failsafe package. After that i wanted to install the reinstall package but an error came up "Failed to validate package certificate". So i pressed the Start-Stopp Button another time so the ignition goes on and turned off the car. After that i tried to another time so pressed the Start-Stopp Button and the MZD comes up. Everything fine. I wanted to check the USB stick on computer if there is anything wrong. After that i tried another time. So i pressed the Start-Stopp Button one time and the Screen remains black.

Radio is still working and chaning the Volume works.

I've tried to reset the whole system over the settings menu. Nothing happens.
Also the soft reset (BACK + MUTE + NAV) changes nothing.

I've searched the forum for an solution and found out that there is way over SSH.
But without an tutorial.

Is there a way to safe my system or should the dealer do this thing?

Thanks for helping