I've got a Pascal nvidia card that Ubuntu doesn't understand, and instead of automatically booting into a low graphics mode it just blanks the screen. I could install Ubuntu by editing boot parameters and using nomodeset but I can't do that once it's installed. Holding down right or left shift does nothing. Is there a way I can boot into Ubuntu?
You can use the boot repair tool to reinstall grub with a menu delay. This will allow you to add the nomodeset option to your kernel by pressing 'e'.
Once booted, enable the nvidia driver in the 'additional drivers' application and reboot the computer, this time without changing the boot settings.