We don't have a formal repository of these, but if you feel you can write one, please go ahead!
I've also been looking for that one several times, and didn't find one on Ask Ubuntu last time I looked either, but I never got around to doing it. Ideally this should be written while testing in a VM, which takes a bit of time.
Michael Mrozek found after BIOS splash, will not boot, asked to select OS, but can't, which is a pretty good reference for Grub2 on Debian and derivatives.
If you write a canonical answer, be sure to state which distributions it applies to. Different distributions set up Grub in different ways. I think terdon's answer is suitable for Grub 2 on Debian and derivatives, the Arch wiki probably has something good already, which leaves Grub 1 on Red Hat as a major candidate for a canonical question (unless this is covered in the RH manual).