[SOLVED] Flashing a New ROM to My Lenovo S650 Smartphone

There are different reasons why a user will want to flash a new ROM (system) to his smartphone. For me, the simple motivation is that my Lenovo S650 is sadly not with Play Store...yes, very bad, which is very common for a phone from China - with the Play Store taken away!

(1) Find a ROM file for the model of your smartphone
The first thing you do is to find a new smartphone Android system (the ROM file). Simply google it, search for your model, like in my case, search "Lenovo S650 ROM download". The search result shows a number of links to download. Be careful of some websites which may like to trap you to advertisement or getting your information instead of generously helping you...

If your smartphone is powered by Mediatek chipset, here is a good source of MTK ROM files for different brands and models:
http://www.mtkfirmware.com/firmware-downloads


(2) Extract all the files of the ROM package your downloaded
Often, the downloaded ZIP file is with everything you need. If not, you can still go to here to download the needed tools: http://spflashtool.com/

(3) Install the smartphone USB driver

Either you install directly from the downloaded ROM package file, or you can follow these links to download the needed drivers.

http://spflashtool.com/download/MediaTek_USB_VCOM_drivers.zip

http://spflashtool.com/download/Driver_Auto_Installer_v1.1236.00.zip

(4) Run the SP Flash Tool program

Either you run the SP Flash Tool program with the ROM package, or you can follow this link or go to the website http://spflashtool.com to download the SP flash tool. 

http://spflashtool.com/download/SP_Flash_Tool_v5.1628_Win.zip

Run the tool, named "flash_tool.exe". It looks like this:

(5) Go to the "Download" tab, press the "Scatter-loading" button. Select the scatter file, which is located inside the folder of the extracted ROM file. It's named like "MTxxxx_Android_scatter.txt".

From the menu, select "Options". In the Options window, select "Download" at the left side, check both options for "DA DL All with Checksum". Close the Options window.

Just below the "Download" button, there's a drop down box. Select "Firmware Upgrade".

(6) Press the "Download" button. The application is now stand-by waiting until a smartphone is detected as plugged into the computer USB port.

(7) Remove the battery from your smartphone. Press and hold the Volume Down or Volume Up key while connecting your smartphone to the computer using a USB cable, until the flash_tool application showed the status change as the smartphone is detected.

(8) The status bar will show the flashing status. When it's completed, a green check message "Download ok" will be shown.

(9) Close the flash tool application. Disconnect the USB cable and power on your smartphone again.


Additional Reference: https://androidmtk.com/ provides useful information on the MTK flash tools.