I can confirm that the full procedure covered in #1 and #5 has worked for me once I added one addition change. I found a file in /etc/modprobe.d with the line "alias nvidia off" which prevented bumblebee from loading the nvidia module. It was in /etc/modprobe.d//blacklist-nvidia.conf which I believe is created by prime-select and remained although nvidia-prime had been purged. I commented out the line and restarted bumblebee with "sudo systemctl restart bumblebeed" and everything then worked.
I can confirm that the full procedure covered in #1 and #5 has worked for me once I added one addition change. I found a file in /etc/modprobe.d with the line "alias nvidia off" which prevented bumblebee from loading the nvidia module. It was in /etc/modprobe. d//blacklist- nvidia. conf which I believe is created by prime-select and remained although nvidia-prime had been purged. I commented out the line and restarted bumblebee with "sudo systemctl restart bumblebeed" and everything then worked.