Just in case anyone has some ideas, on how to convert a US Zumo550 to support Japanese v10 map.

I hope some of the gurus here can offer some ideas/advice.
I have a US Zumo 550, and having just moved to Japan I am trying to make it work with a Japanese Garmin map.
I can load the Jap Map OK, but obviously it just displays as gibberish since the US Zumo can "read" Japanese double byte characters.
I have a "dump" of a friend's Japanese Zumo 550, so I have all the files that come on that version. My assumption was that at the hardware level, the Zumo, like a PC, can support either type of system, as long as it's running the correct firmware.
To test this assumption I've copied over the main (from the Japanese unit) files found in the Garmin folder on the Zumo. With these files in place my logic was to run the Japanese version of the GUPDATE.GCD file (which simply involves copying it to the Zumo, into the Garmin folder). Thus once the unit is restarted the GUPDATE.GCD file should upgrade/change the OS on my US Zumo to Japanese. Btw, this is how the Japanese Zumos get updated, i.e. the user downloads the new firmware file and restarts the unit; the nice Web Update program we can use on the US units is not supported/developed for the Japanese version.

Despite the logic above sounding OK, I'm having difficulties with the execution part, I can see the Loader running, but after a little while the Zumo simply shuts off. I can't figure out what I might be missing to make this process work. (again, I have already copied the Japanese gmapbmap.img, gmappromimg, GarminDevice.xml (updated this file with my ID#), the corresponding .sum files, and everything else to my ex-US Zumo...
I've tried doing a hard reset and pulling the battery, but still get the same result of it not finishing running the Loader.

Would really appreciate any helpful advice.