[X4U] Startup key combos don't work

[jeff]

G4 MDD, dual 1.0, 2 gb ram, 10.2.8

*None* of the startup key combos are working on 
my MDD. Pressing the pmu button does nada as far 
as I can tell. I've looked around and haven't 
found anything at all about this.

None of these work:

Cmd-Opt-P-R  .....          Zap pram
Cmd-Opt-O-F     ......       Open firmware
C                      ......          Boot from CD
Opt                   ......          Select startup disc
Cmd-Opt-Shift-Del  ...   Ignore startup volume

And like I said, pmu reset seems to do nothing, 
although I'm not sure it would be obvious. My 
reading says it resets clock "on some models".

Machine boots fine from either of 2 internal HDs 
or CD as long as they are selected first in 
startup disk sys pref.

I've tried one ADB and two different USB 
keyboards and three mice, including original 
issue (with the G4) apple. My usual setup is an 
ancient Apple adjustable ADB via adapter and a 
Logitech wireless mouse.

FWIW, the Apple hardware test came back clean, 
and I've repaired permissions. No disk problems 
reported .

I am more than baffledŠŠŠŠŠ

Any ideas?

Thanks in advance,

jeff