Reserch Download tool is the most inportant softwares for flashing, downgrade, upgrade any SpreadTrum CPU Chipset where ever is an android system or not android smartphone.
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Step by step flashing tutorial can look at here => Flashing samsung c3520i | Flashing lenovo 238t | or can looking image below do to run the RD tool.
learn how to use RD Tools.
*) Research Download tool is an softwares made by Spreadtrum comunication.inc for full credit this software / tools.