I don't move kext AMD to DisabledExtensions
@Motion2K Are we having the same problem? My Mid 2011 27" iMac's GPU seems to have just croaked. Running normally then froze on a blue screen with faint vertical stripes. Turned it off and it won't boot up all the way now.
Single user mode boots fine. Normal, safe, recovery, and internet recovery boots get to the point where the video driver is loaded, but then show some minor graphics corruption, flash to a black screen, then freeze on a grey screen. Since I can't boot Recovery, I can't disable SIP to rename/move the GPU drivers to get other boots to go.
I'm going to grab a thunderbolt cable and tether to the iMac up in target disk mode to move the GPU driver extensions tomorrow. Apple seems to have a replacement program for my GPU, so at least there's a silver lining.
I don't want to hijack your thread, though. Were you able to get your mac booting?