ubuntu not booting past grub2

[COLOR=#111111][FONT=Ubuntu]I installed Ubuntu on my 2012 Macbook Air. Everything worked well, no issues with dual booting Yosemite and Ubuntu. Then I did a software update and could not longer boot into Ubuntu. Instead each boot gets stuck on the Grub2 black cli screen. I can boot into Ubuntu if I type exit then let the system reboot then type exit again. How can I fix this so the Grub correctly boots Ubuntu without this hassle?

This is what I see when I boot into my Ubuntu partition:

Gnu Grub Version 2.02-beta2[/FONT][/COLOR] [COLOR=#111111][FONT=Ubuntu]Minimal Bash like editing is supported for the first word TAB list possible command completions. Anywhere else TAB lists Possible device or file completions.[/FONT][/COLOR]

Looks like something is borked into the grub config; reinstall it sudo apt-get install --reinstall grub-pc

Moved to Apple sub-forum since a Mac.

Is system installed in UEFI boot mode? I thought Mac used UEFI, but not familiar with all the versions. Then reinstall may not be grub-pc but grub-efi-amd64.

https://help.ubuntu.com/community/MacBookPro

[COLOR=#000000]grub-efi-amd64 is installed. I will reinstall it and see if that helps. [/COLOR]