Third time's a charm?

I haven't tried that iso, but I've added the non-free firmware to the standard .iso. I get a completely clean boot (nothing called out by dmesg) but the blank screen after boot persisted. There is a known kernel bug that causes this, but it doesn't get fixed until a much newer kernel. I've installed Debian 11 and Linuxcnc 2.9 this morning. That all went really well, but the parallel port is not responding. Since you asked for details, I'll try to figure out how to tell which chipset it uses, but its the same exact board that was working, as recently as yesterday on the MSI (when it has 2.9 installed but not 2.8).

Pick one machine to work with, install Linuxcnc and get it to boot.
Supply the info asked for regarding the parallel port as requested earlier. You were supplied with a link on how to do that.
Reread the post regarding the use of the Parallel Port Tester.
Please be consistent, swapping and changing is not helping.
Please try to approach this in a rational manner. You are not helping yourself.

I think you need to quantify that the first time you modify the kernel commandline is at the grub boot screen. Also it maybe an idea to delete quiet & splash so you can see the kernel messages.

Thanks, I tried the nomodeset thing last night--no luck. There are lots of similar threads and that change helps some people, but not all. In my case, it made no difference.