Thanks for the kind words.

I had opened up the unit and found I could not re-attach the USB connector because some of the traces had been lifted off the board. However, I cut off the B side of a USB cable and soldered this cable's black and red wires to a ground trace and the trace that used to be the USB connector's +5V pin. I also connected the ID pin to +5 (otherwise it seemed to hang waiting for a USB connection on boot-up). This gave me a fully functional unit. I was able load maps and even custom PoIs via the SD card. So I'm very annoyed at myself for not quitting while I was ahead.

My problem may be related to the fact that when the Nuvi is configured like this it seems to go through a different boot process than when the USB port is functional. I don't doubt that in normal situations this method works. That's why I thought it worth warning others who may be trying to do firmware upgrades with non-functional USB ports.

Setting/System/About shows the Software Version is still at 2.30 while the Keyboard version is "Unknown" and the Audio version is "Missing" so perhaps the problem is that the update to 4.00 did not complete or somehow went haywire. I'll try disconnecting the ID pin and to see if the different boot sequence causes the gupdate.gcd to get loaded (no amount of power cycling or erasing user data seems to do it).

Otherwise I may have to resort to using ldr.bin and update.txt as I think you are suggesting.

Thanks again.