How can I boot in single-user mode for terminal with grey screen? It all started when I wanted to sell my old Macbook 2011 and remove it from iCloud. I clicked delete my Macbook in iCloud. AND Whoup!! My Macbook shuts down and deletes itself....
I reinstalled High Sierra, unfortunately my AMD graphics card hasn't worked for years. But at that time the card was bypassed.
BUT NOW
I can't disable the graphics card via CMD+S.  It stops loading &quot;HID: Legency slim 2&quot;.
I got the problem after the PRAM reset.
when I followed the instructions...
https://gist.github.com/cdleon/d1eff7246a25193304284ecec40445b0
NOW I also can't get into Recovery Mode with CMD+R.  Also not via internal or USB stick. I ALWAYS get a gray screen.
How can I disable the graphics card to set up the Mac?
I get prohibition symbol... i need a terminal! :(
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It might be easier to boot in target disk mode to erase a machine that’s not healthy enough to boot to recovery. As you know, you’ll need to assemble an external OS and modify it to prevent graphics drivers to get around your failed GPU / logic board. Target disk mode often works in this case since only the firmware is running - no OS.
Both of these require you have another Mac running in my experience.

https://support.apple.com/guide/mac-help/transfer-files-mac-computers-target-disk-mode-mchlp1443/mac
https://support.apple.com/en-us/HT201255

Option is the startup manager you need if Internet Recovery or built in recovery fail.