I see this is an old thread, but I am having an issue with this same text screen upon trying to boot from an external USB to do a restore. Im on the latest High Sierra. 2009 MacPro 5,1. SSD in bay 1.
Im fairly certain I began getting this text screen on bootup after I installed a 980 ti gpu about 2 years ago. Never had any problems. It would just show the text and go to the apple startup screen. But I'm fairly certain that any boot keystrokes would never work after that. IDK if this screen was the first in the chain before it lets you do any recovery functions or what but i could never do any recovery, startup manager, pram zap, etc.
Anyway, I installed an audio plugin that messed with some other plugins and I couldn't get it fixed. I do daily clones of all my drives with CCC including a bootable of my OS onto external USB drives. So i was just going to restore to that morning's clone. I changed the startup disk to my external USB bootable clone of my Mac HD. restarted and then got the verbose text as usual, but then it just stayed there with the question mark folder.
I've contacted CCC and a local MAC repair. They gave me several suggestions all of which I've done with no success. swapped keyboards, removed all peripherals, SMC reset, bootable OS thumb drives. Its as if this text screen is in the chain before it allows anything else like keystrokes or the recovery functions to happen and its just staying there. CCC said if it doesn't find the USB drive I designated, then it should look for any bootable device. My Mac HD is still there as always, IDK why it wouldn't find it. Yes, there is a small chance it suddenly died, but again, I was not having any issues like that when I went to restore. In fact, never a single issue on this machine ever. This SSD is a Samsung EVO Pro, 1 year old, 99% health a week ago. no power surges, lightning ( I also have a big rack power conditioner surge protector). I realize anything is possible, but i'd say improbable. Either way, no luck with any bootable USB drives, both with my bootable clones and the apple downloaded bootable OS on thumb drives. The drives are all smaller than 2tb. They seem to have activity by the light on the drives but I've let them go even overnight and nothing changes...question mark. CCC said it should find the OS drives fairly quickly but it would be the apple progress bar that would take some time. So I can't get to that past this text screen and the question mark.
My screen is virtually the same as the one at the top of this thread. Still says stuff about fusion drives, which I've never owned. Again, I've had this screen for about 2 years with zero problems ever...until i tried to boot from an external USB drive. One reply stated that when they swapped back to their original GT 120 gpu that the text stopped appearing. Mine was bought with an already upgraded Quadro card, that I then upgraded to the GTX 980 TI, which is when I believe I started getting this text and stopped being able to use any boot keystroke functions. Yes, I tried putting the Quadro back in several times, but I kept getting high pitched whine or tone when I would power up so idk what is up with that issue. I've just bought an old gt 120 and I will try that and see if it gets rid of that text and lets me boot up. Just waiting for that to arrive. I feel like I just need to get back in to tell it to just boot like normal from my HD as always...nothing was really wrong except the minor audio plugin issue.
Any thoughts or experience with this issue? In the end, if the 120 doesnt work, I'm thinking about just buying another MacPro with the same basic specs, mainly the CPU and just swap everything over. I have clones from that morning before the plugin issue of all of my drives including 3 of my OS drive.
Thanks,
Shawn