The ROM used in this tutorial is the latest Official Release Candidate (RC5) till this post date, with 5.1.1 Android , to Jiayu S3 who have come from Germany jiayu.de. So this is the must stable version who have come out, made by the company. This ROM is not pre-rooted from factory.
This tutorial was made for upgrades from Android 4 to 5, and updates in Android 5. Make sure you do a backup of your data until you start.
0 – Download this package, here you have all you need for this tutorial: LINK
1 – Connect your smartphone directly in the motherboard, dont use extensions. If you are using a laptop, connect your smartphone where you have the major part of your laptop connections, there will be your motherboard. Dont use cheap usb cables to flash smartphones or with problems of connectivity! Now connect it turned ON and check if you have more than 50% of battery, if not leave it charging.
2 – Extract all the content in the package that you have downloaded and install PdaNetA4190.exe.
If you sucessfuly install it then reboot your pc (you will receive a notification in your smartphone during the installation). If not jump to the end of this tutorial.
3 – Disconnect your smartphone from your computer.
4 – Extract now the content in the package SP_Flash_Tool_v5.1452.00.zip and open SP Flash Tools from the extracted package.
5 – NOTE: Ignore the list that i have in this printscreen, it is supposed to be empty.
6 – Extract the content of the Jiayu_S3_5.1.1_rc5_flashtool.rar package and then go to that folder and choose the MT6752_Android_scatter.
9 – Now if you have already installed a recovery before like CWM or TWRP, your must uncheck the recovery option. If not you just need to choose first Firmware Upgrade and then click Download.
10- Now you must turn off your smartphone and connect it on your pc.
11 – Then if you have made everything fine you will see it moving and you must now wait.
12- And then an Ok popup will happear.
13 – Now you must unplug your smartphone and turn it ON and you will enter in your new installed rom.
If you cannot install the driver in your pc, you must try in another pc with Windows 7, the best OS to lead with mediatek smartphones. If you still dont have another pc to try a shot, install a virtual machine with VMware workstation (https://my.vmware.com/web/vmware/details?downloadGroup=WKST-1007-WIN&productId=362&rPId=8482) and install a Windows 7 with 32bits, and repeat this tutorial on your pc running your vitual machine. For more information check this tutorial on how to use a virtual machine: https://www.youtube.com/watch?v=w591rYXjl7g
If you are not familiar with using virtual machines, to remove and add devices you should go to the upper left corner and choose Player >> Removable Devices and you will see all the devices you have connected to your pc and what devices are connected to your virtual machine. You cannot use a device at the same time on both sides (virtual machine + your physical pc).
This process was used by me using a virtual machine with windows 7 86x.