flash new rom

Jul 8, 2014
Hi, I've been trying for serveral days to update the ROM of my Mi3 TD-SCDMA without any success.
It doesn't have the updater app, i've tried installing it from the apk found at miui_MI3_JXCCNBE21.0_47ad702550_4.2\system\app\ but it fails. Also tried the MiPhone app, putting the phone into fastboot mode but MiPhone isn't detecting it at all.
How can I do this?
Jul 13, 2014
Hi I have a brand new Xiaomi mi3 I got one week ago. It is authentic cause we checked it out, however it did not come with an updater app. I can't update it to miui v5 now. What do I do? I have tried everything already, thank you