Ubuntu Mate 16 Intro Load Fail Nvidia

I recently installed Ubuntu 16 mate, and everything worked great. Last load I switched the display driver from the community open source to proprietary Nvidia (for my GTX 970). Everything seemed fine and I turned the machine off, rebooting the machine I now get the mostly grey (with green border) screen, it flashes a few times, over about 15 seconds (boot to desktop was about 5 prior), and then I see no display input on my monitor, I"m not sure if Ubuntu is loaded or not in the background. It should be irrelevant but I’m technically booting this on one separate hard drive, with windows on another and selecting which OS to boot from the bios boot order (not grub), but I doubt that is relevant to the issue. How can I troubleshoot this, can I force command line and switch drivers or anything like that?

From the grub menu, select “Advanced options for Ubuntu” and then the latest kernel with “(rescue mode)” appended.
This boots into a text-mode menu from which you can open a root shell and do various repairs.

I’m not sure grub is installed, I selected Ubuntu mate full install on the entire disc, default options I believe, but I don’t see any grub popup. Any ideas?

Hi @bobbydoogle,

this shows you how to display the Grub menu with a single OS install:

This shows you how to fix driver problems in recovery mode!: