Download latest Android 4.4.2 Kitkat stock firmware for Umi Zero smartphone from here or from here. (flashable from Windows PC via USB cable). Download previous firmware from here.
Archive name: UMI ZERO MTK6592T 182763 20141217 / Y800
Archive file size: 358 MB
Project: ratech92_cwet_rlk_kk
Platform: MT6592
config_version: V1.1.2
Upgrading notes (see this video tutorial)
1 – Download & unpack FlashTools. Run Flash_tool.exe
2 – Unpack Rom in folder
3 – Select MT6582_Android_scatter.txt in folder on rom. And wait.
4 – Check Option->USB Model, click USB Model
Choose Option->DA DownLoad All->Speed->High Speed, click High Speed
5 – Turn off your phone, remove the battery.
6 -"Press F9 (or hit Download button)"
7 – Connect your phone into the computer with USB data cable.
8 – The process will start and a red progress bar will appear after color purple, yellow.
9 – And green circles display.
10 – Boot your phone
11 – Restart
12 – Enjoy
