Wer hatte die gleiche Frage?

Hello, I spent hours and hours yesterday making different USB sticks, trying to make my new laptop boot from them. This is my model:

https://www.medion.com/gb/service/product-detail/30031974

As you can see, there are no technical specs, but it's a PC, and as a PC, it should boot from bootable USBs.

I've tried GPT, MBR, FAT32, NTFS, with and without Secure Boot, and the outcome is one of the following:
1. Boot menu -> Choose USB -> Thrown back to Boot Menu

2. Boot menu -> Choose USB -> Black screen with static _ in top left corner, with text "Secure Boot disabled" on a second line. Low resolution.

3. Boot menu -> Choose USB -> Black screen with static _ near middle of the screen. High resolution.

Do Medion notebooks feature some special block against anything that isn't Windows?

Big thanks in advance for your help, and your patience with my frustration.

Masklin