mine was 1.1 . i changed the product code and used nokia software updater. At the end of the installation it gave error or sth. İ tried the open and it said warning about changed firmware. So i used win flasher this time to flash with images from navifirm.

at first flash,it finished with success for 1.2 but gave warning as well

at second for 1.1 gave error but completed. (simcard errors after boot)

at third for 1.1 again gave error at the end (simcard errors again)

errors :
bb5 rdc cert read failed
mtc nos ready not received

note: i used navifirm+ nokia care suite to download