On this page, you will find the direct link to download Cubot GT90 Stock Firmware (flash file) from Mediafire. Firmware contains Flash Tool, Driver and instruction manual.
How to Flash Firmware
Step 1: Download the stock firmware on your computer.
Step 2: Rename it to update.zip.
Step 3: Place it in the Phone SD memory.
Step 4: Flash it through the recovery.
[*] Before flashing the above firmware, please take a backup of your personal data. So, that you can easily restore your personal data on your Smartphone and Tablets.