Hi and welcome to Just answer.
Initially, please try step on the foot pedal after few minutes (expected the machine booted up completely). If the needle goes up and down even without screen, you have faulty LCD monitor/screen that need to replace by authorized Bernina dealer. The LCD screen is not repairable.
If the needle won't move after you step on pedal, your system is not boot up the possible problem are main cpu board or power board. That is dealer job also..
Possible DIY remedy.
Please note: The answers/solutions above are for non-pro users. If you have experience on electronics and have knowledge on using multimeter just let me know and I will help you to troubleshoot your machine.
Hope this information will be helpful.
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I'm just following up with you to see how everything is going. Did my answer help?
Let me know,Chester