[CentOS] The case of C6, grub, and the missing menu

Fri Jun 30 13:48:53 UTC 2017
m.roth at 5-cent.us <m.roth at 5-cent.us>

An important server accidentally got rebooted yesterday (ahem, shuffle).
On boot, it insisited on an fsck. So I rebooted, intending to get to the
grub boot menu, and tell it fastboot.

Nope. In grub.ocnf, it's got timeout=5, but I'd see the std. POST, a blank
for a very short time, then it would be booting. By repeatedly type "e" I
got into the menu once or twice, but trying to edit a line, it would
suddenly start typing by itself (and no, the keyboard's just
fine, thank you).

The question is, why did it never offer me the menu? Everything looks
normal to me in the grub.conf.