Macbook pro 15′ 2011 gpu fix disable

This worked for me:

1. boot using Command + s
2. manually type nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00 and run it
3. manually type nvram boot-args="-v" and run it
4. reboot
5. boot using Command + r (this time it boots fine, no grey screen)
6. disable SIP: manually type csrutil disable and run it
7. manually type nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00 and run it
8. manually type nvram boot-args="-v" and run it
9. reboot
10. boot using Command + s
11. manually type /sbin/mount -uw / and run it
12. manually type mkdir -p /System/Library/Extensions-off and run it
13. manually type mv /System/Library/Extensions/AMDRadeonX3000.kext /System/Library/Extensions-off/ and run it
14. manually type touch /System/Library/Extensions/ and run it
15. reboot