So after battling for two days, finally I have managed to solved this problem.
First of all download stock ROM for your tablet from here
and extract the file anywhere you want.
Note:- All the below steps are provided in .ppt file which you can find in the downloaded zip folder(here ..\BSNL-IS709C\BSNL IS709C\Firmware\upgrade\tool). Since it is a Chinese version so I thought it might help if I re-write the steps here:
- Shut down your tablet.
- take out your SDCard if you don't want data loss.
- Plug one end of the Usb cable to PC/Laptop.
- Press the middle button(namely menu button) of the three buttons on the tablet and the power button together and then plug another end of the Usb cable to the tablet.
- After this, your computer will try to install drivers for your device which you can ignore because you are gonna install the drivers manually.
- go to device manager->Other devices->right click on the unknown device(which is yours with yellow triangle) and then click on update driver software.
- Choose to manually locate drivers and move to this directory (..\BSNL-IS709C\BSNL IS709C\Firmware\upgrade\tool\Driver).
- Select the appropriate driver(x86/x64) and click OK, a red color pop up is displayed. Click yes(or whatever) to install the drivers.
- Now open the RKBatchTool provided here(..BSNL-IS709C\BSNL IS709C\Firmware\upgrade\tool). You will see a green color square on it which means that it has recognized your device. Meanwhile is the Chinese version, so can refer this picture for further operation:
- Click on the Restore button to factory reset the tablet and when its done. Click on upgrade.
- Restart the tablet and voila, its done!!