Taken from StackExchange
Thanks to LangLangC
For temperature and other improvements see https://gist.github.com/cdleon/d16e7743e6f056fedbebc329333d79df
Shutdown, unplug everything except power and hold
leftShift + Ctrl + Option + Power
I holded for 5 seconds, but holding just for an instant should work
Command + Option + p + r
Until you hear the startup chime two times.
if you are on high sierra 10.13.6+ you might need to use
Command + r
instead
Command + r + s
csrutil disable
nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00
nvram boot-args="-v"
reboot
Command + s
It might look as if it hanged, but press enter and you should see the shell (root#)
/sbin/mount -uw /
mkdir -p /System/Library/Extensions-off
mv /System/Library/Extensions/AMDRadeonX3000.kext /System/Library/Extensions-off/
touch /System/Library/Extensions/
reboot
It will show a bunch of text in the screen (don't be alarmed, let it finish) and then it will restart again In second restart it will show text in the screen again and then it will show normal login screen Your computer now should work properly (dGPU off and iGPU on, shown as i in gfxCardStatus
If an update that contains changes to the AMD drivers is about to take place it is advisable to move back the AMDRadeonX3000.kext to its default location before the update process. Otherwise the updater writes at least another kext of a different version to its default location or at worst you end up with an undefined state of partially non-matching drivers.
After any system update the folder /System/Library/Extensions has to be checked for the offending kext. Its presence there will lead to e.g. a boot hang on Yosemite and Sierra, an overheating boot-loop in High Sierra.
If any of you are totally unable to boot into Mac-OS, this happened to me at some point and I was left between losing total usability of the laptop or installing Linux, so I installed Pop!_OS at first and then changed to Ubuntu just because it's update cycle is more frequent. I left a very messy log of the process in my blog, I apologize for the adhd mess of the write up, but it works: [How I Installed Ubuntu 23.04 on a Late 2011 Macbook Pro (for the Second Time)](https://www.sp-cy.com/note/how-i-installed-ubuntu-24-04-on-a-late-2011-macbook-pro-for-the-second-time/)
Unlike OS X, everything works fine on Linux, maybe battery life is not as good but the rest might be even better. For me it was just impossible to access Apple servers to reinstall the OS on a completely wiped SSD, so this was my best option. Hope this works for any of you that is left with an unusable laptop due to Apple's neglect.