[commodorejohn]

Hm, interesting. So, just to be clear, this is the observed behavior:

NVRAM in, keyboard in: boots to serial console, runs some tests, prompts for a selection between booting normally, dropping to an OpenBoot prompt, or some third option I can't remember. Requires a password before actually allowing you to boot or go to OBP.
NVRAM out, keyboard in: boots to serial console, announces that it will POST, apparently hangs from there.

I can't remember if I've tested it with the keyboard out or not, but if I did the results weren't any different. (Not sure if the computer would even perceive it as "out" or not, since the adapter box has to be connected in any case.)

It's definitely interesting that it defaults to the serial console even with the NVRAM out; I thought the default behavior was to switch to the framebuffer if the keyboard was connected? It may be that the POST happens before the switch to framebuffer console? I'll double-check the seating on the framebuffer card, and I'll definitely give the NVRAM reset a try.