The messages you’re getting sound like they’re from the bootloader, so I think secure boot is not causing the problem… Linux should print some stuff right away when it loads, maybe check the architecture of the kernel you’re trying to boot, even an error immediately after loading the kernel should print something unless the architecture is so different that it’s just feeding the CPU bad instructions… Not sure how the bootloader would get installed correctly in that situation though. Is this after installation? Does the system boot from a live USB or cdrom?