Here is my report after defibrillating the Sony last night:
If Neal had not warned me, I might have given up. Those buttons had to be pushed in less than a second after each display change. I could not do it fast enough until I make a cheat-sheet with the correct order.(Menu+Format,Format,Guide,Exit,Format) And yes, it still looped about 3-4 times after the Clear NVM operation was complete. I could see, however, that the clock dashes and subsequent numerals stayed on the display a little longer each time. Finally, I hit the power button, and it fired up.
Mark & Bill: As if just to prove that the same actions can produce different results on our individual machines (depending on various factors), I did not lose .21 firmware, but I did lose the grid. (although I suspect it was lost earlier)
I did need to reboot manually several times after the Clear NVM to get my CableCard to work, and it is now functioning as a tuner again.
Manual recording is all but crippled however, because the "not in your lineup" error will not allow me to record any HD channel. And since I lost the grid, I cannot use that as a workaround anymore. Switching the tuner away from the channel and back (as well as other tricks) were unsuccessful. Maybe the next CableCard update will change that. Either way, I will try more rebooting later. (which has solved CableCard problems in the past)
So, my Sony is not quite a brick, but currently less than what I will settle for. I will be looking for a TiVo on eBay, while still playing around with the DHG. After watching all my previous recordings, I might wipe the HDD to see if that helps.
Thanks to all who chimed-in!