Hello @PLage1 ,
Try to recover your bios with Security Jumper removed:
Bios Recovery with Security Jumper removed: https://www.intel.com/content/www/us/en/support/articles/000005532/mini-pcs.html
1.Prepare USB stick fully formatted to FAT32 with Bios file HN0053.bio https://downloadcenter.intel.com/download/28458/BIOS-Update-HNKBLi70-86A-?product=126143 . Format your USB with Quick Format option unchecked. Do not format your USB in MAC (OS) or Linux machine. Use Windows.
2. Disconnect the power adapter and remove the upper cover and the LED panel from your NUC. Disconnect the LED panel connector before panel removing.
3. Remove the yellow security jumper (see Product Technical Spec, para. 126.96.36.199, page 46 ) and close the bottom cover. https://www.intel.com/content/dam/support/us/en/documents/mini-pcs/nuc-kits/NUC8i7HVK_TechProdSpec.p...
4. Insert the USB with the HN0053.bio file.
5. Reconnect the power adapter and power ON the NUC. Wait 30 sec - 2min. The Recovery process will start automatically and will end after 2 -5 minutes.
6. When bios recovery completed, switch the power OFF, remove the power adapter and replace the Security Jumper (pins 1-2) . Reinstall the LED panel and the upper cover.
7. Power your NUC ON.
Hope this will work