You tried NSU or not?

Go to this page:
http://www.nokia.com.my/support/download-s...software-update

Then select your model.

Then, download the Nokia software updater 35MB one.

After that, can install and follow the instruction to update your phone.

Please do not plug your phone into your computer while installing and use original cable PLUG DIRECTLY into the computer's high speed USB port (not through any USB hub). If possible, try to update using the laptop with its battery attached.

You need to change the product code to get the chinese language pack.

Ya. Something like that.

It will be updated to the latest version no matter what.

If it is the latest ones, i think after you change the code, it should not be a problem for you to actually update again although the version still should be the same.