Well, I sent it off today. When I tried to reload the firmware yesterday I had it connected to a USB port on my computer, but not the same port I used for the first firmware flash. The first time I flashed it using a USB 1.1 port which is built-in to my notebook computer. For this last attempt, I used a USB 2.0 PCMCIA card inserted into a PCMCIA slot. If the USB 2.0 PCMCIA card was somehow incompatible with the N800, or incompatible with Nokia's flash program, then the N800 would not have entered the firmware upload mode, which is of course what was observed. I should have tried it with the USB connected to the older USB 1.1 port that worked for the first flash operation, but of course I was following Nokia's flashing instructions which failed to mention that the firmware upload mode was entered by powering on while connected to a computer's USB port, and that holding Swap key was superfluous.

It will be interesting when the N800 comes back to me. I will check it out with both my USB 1.1 and 2.0 ports. If it won't go into flash mode while connected to my USB 2.0 PCMCIA card that would indicate that I need not have sent it off for warranty service.