Yep, that was the same post I found also. It didn't work, and I found another board with a cut/paste copy where someone else confirmed it doesn't work.
Looking at the service manual, I see a reference in the "Starting Diag" section (Page 41) that says:
PRESET INHIBIT (Initialization inhibited) / PRESET INHIBIT
RAM initialization is not executed. Select this sub-menu to protect the values set by the user.
PRESET RESERVED (Initialization reserved) / PRESET RESERVED
Initialization of the back-up RAM is reserved. (Actually, initialization is executed the next time that the power is turned on.) Select this sub-menu to reset to the original factory settings or to reset the RAM. Any protection history will be cleared.
That would seem to be exactly what I want to do, however it's not clear, or I'm to confuzzled to actually execute it. I was able to start the unit in diag mode, changed to Preset RSRV and power down. Wait 1 minute, power the unit back up.
Still can't bring up the SET MENU to appear! Only the OSD Mode appears. Perhaps the Optimizer Mic port can't see I've got the microphone plugged in?