This is not flashing a custom ROM, but rather flashing another official Garmin ROM onto your phone from another country.
Try this at your own risk. Consider yourself warned.
This is reportedly working fine on the A50 (Garminfone) & A10.
I found this posted over at Howard Forums by "vs2".
I wiped my T-Mobile Garminfone and put A50 firmware for Canada's Videotron on it. It works fine and does not have the "offers" etc. that bloated up the T-Mo version. Traffic works just fine too. I now have French rather than Spanish on it.
You may need an unlock code. I did after I did a Master Clear. But if I did not do the master clear, I was fine...
Instructions: (worked for me)
1. Have two micro SD cards
2. On one put the same update file that is already on your phone.
2. On the other put the new firmware you want to update to.
3. With phone off practise taking phone cover off/on and removing SD card.
4. Turn phone on with SD card that had existing firmware update on. Update notice will show and ask if you want to update - say yes, then it should say update is the same as already on your phone do you still want to update, don't accept or decline. Now quickly pull off cover and exchange SD cards and put cover back on. You may get a message about battery cover - go ok. Then the same 'do you want to update' message should appear - go ok.(you may need to pull down the yellow exclamation from the top to accept the update if the window does not show) Be patient and wait your screen will show 'verifing' then reboot and could be a black screen for 10-15 minutes. (try it with out a Master Clear first, your apps will still be registered and you may not require an unlock code!) as your old settings/apps will still be on phone. It may be ok to leave them on??
Some countries have packaged them inside an .exe file (OPTUS for Australia). I used WinRar to extract them from the .exe and followed the procedure above.
http://www.garminasus.com/fr_CA/supp...e-updates.html French Canadian adds French to the languages and removes Spanish.
http://www.garminasus.com/da_DK/supp.../open-a50.html OPEN market. Denmark. .exe file.
http://www.garminasus.com/da_DK/supp...lenor-a50.html telenor Denmark. Also an .exe.
http://www.garminasus.com/da_DK/supp...telia-a50.html telia Denmark. .exe file.
http://www.garminasus.com/en_AU/supp...e-updates.html an .exe for OPT in Australia
http://www.garminasus.com/zh_HK/supp...e-updates.html Hong Kong updates.
http://www.garminasus.com/en_MY/supp...MYS-update.zip Mylasia update.
See vs2's posts on/about page 12 of this thread: http://www.howardforums.com/showthre...-Mobile/page12