Hi. I have been reading these threads about AMD GPUs failing and giving black or distorted screens at boot. I am writing here to drop an idea. I hope this helps, if not, just forget it. :)
Could you make the system detect the unsuccessful boot failing to load the graphical desktop interface, for example memory consumption is not rising or some process initiated at a late stage has not loaded after some seconds/minutes? Then, if you can check for this, you could make the system reload the graphical interface with the GPU disabled, only using the CPU and then show the user a warning stating that his GPU is not working and that he needs to download firmware X to get it working. Well, I don't know if this is possible/feasible. It just came to my mind because my PCs depend mostly on the CPU (no GPU) to do all the work. I thought that if the old ones could do it, then the new ones could surely do it too. Again, I hope this helps. Have a good day.