This is the case with my old Samsung !
I do not have first hand knowledge of this generation but I believe we see a more securely locked bootloader. When searching further online, or on this forum, check info for beyond(X)lte
Firstly have you had the device online + a SIM card installed. I have seen it reported that on a new device one should at a minimum contact the remote to check if the device is up to date (maybe via mobile data is significant).
Back to Pre-Install Instructions https://doc.e.foundation/devices/beyond0lte/install, USB debugging must be allowed.
Now if you attempt
Power off the device, and boot it into download mode:
- hold Volume Down + Bixby and connect USB cable to PC
- Now, click the button that the onscren instructions coorelate to “Continue” and/or “Unlock Bootloader”.
… do you get any reaction from the device ? Correct timing of the connection of the powered USB cable is important. The illustrated method in Post #2 seems to reasonable, where in that method do you get stuck ?