Firmware download link: http://www.needrom.com/download/colorfly-g708-oc/

Version: Android 4.4.2

ONLY MT6592

Official firmware Colorfly G708 Octa Core version: G708 Oc_SV1.03_KV1.0_20150207 – KOT49H – ALPS.KK1.MP1.V2.29

Gapps include – No Rooted

Language support: Multilang

Tutorial

Unpack FlashTools, and Click on Flash_tool.exe
Select a the MT6592_Android_scatter.txt in ROM
Wait file to be added into Flash Tool>choose Option>USB Model,click USB Model>Choose Option>DA DownLoad All>Speed>High Speed,click High Speed
Turn off your tablet>Press F9 (hit Download button) OR if upgrade ROM Firmware>Upgrade and connect your phone into the computer via USB data cable.
The process will start and a red progress bar will appear after color purple, yellow.
And green circles display
Finish !
You can now safely disconnect your phone and turn it on.