First you’ll need to download the last version of Android, 4.03 right here. Â This will step you up to build V11R42A.
I think you need the ‘version upgrade package‘, although I wound up kicking it via the bootloader. Â Also you have to unzip the 600+MB download, and place it on a SD card on the phone. Â Even though the image will fit into RAM on a zapped set, it’s really picky about reading it from flash.
Now because I’m not in Japan, I had to kick the installer off by shutting down the phone, then turning it back on while holding down the menu & back buttons on the phone.
Granted Android 4.0.3 isn’t exactly modern, but it’s a lot better than 2.3! Â And for what it’s worth, it sure feels a lot more solid after the upgrade.
Having used the phone after the upgrade, it’s faster and the battery life is VASTLY improved. Â If you are unfortunate to have owned one of these phones (or feel unfortunate at it’s 12 hour max lifespan) do yourself a favor and upgrade!