[K3 Note Q&A, Help & Troubleshooting] svs36:
Hi there, I also had the same issue a while ago. I soft bricked my phone, it got stuck into bootloop and I got so confused what to do because I didn't wanted to lose my phone over some parlor trick. What I'm gonna do here is explain you all the things step by step and if you follow them correctly, you will see your k3 working at the end. So first thing first don't ever use kingoroot again to root your phone or any other phone. Not Helpful.

So I'm assuming that you are stuck at boot logo or somewhere around it, facing black screen. Don't worry it'll be alright at the end of the day. You need to download a few things before we start because to completely vanish the problem we have to unroot the device and install stock rom again using spftools.

Requirements Download files and tools :

1)Download flash_tool

2)Download USB Driver of Lenovo K3 Note

Link- https://drive.google.com/folderview?...kU&usp=sharing

3)Download K50a40_S112_150610_ROW.rar

Link- https://docs.google.com/uc?id=0B1tnng1Ipox5S1NsVG53YndVNVU&export=download

After downloading all the necessary files keep your PC ready for the following things:

1)Install "LenovoUsbDriver_v1.1.13.exe", then Restart pc.

2)Extract "SP_Flash_Tool_exe_Windows_v5.1452.00.000.zip" using Winrar

3)Open SP Flash Tool with Adminstrative rights (Right click on flash_tool.exe from inside the SP Flash Tool folder)

4)Go to Options > Option... > Download > Tick "DA DL All with Checksum" > Close the options box

5)Close SP Flash Tool.

Charge your phone up to 80% or more- is a must for the following process to avoid any issues.

Flash Recovery

1)Download and Extract "TWRP_v3.0.0-3_for_SP_Flash_Tool.zip" *

2)Open SP Flash Tool(admin rights), and From "Download" Tab click on "Scatter-Loading"

3)Browse the TWRP v3.0.0-3 folder and select the "MT6752_Android_scatter.txt" file > Ok **

4)Click on "Download" icon

5)Completely turn off your phone and wait for about 10 sec (BUT DO NOT REMOVE BATTERY) and NOW connect it to PC using usb cable.

6)Wait till the Process completes and a "Download ok" box will appear with a green tick. Disconnect the phone from cable. Done!

Now press and hold VolumeUp+VolumeDown+PowerButton all three buttons at one untill you see the "TWRP" logo.

The phone will boot into custom recovery you just installed.

Flash Stock Rom

1)Extract K50a40_S112_150610_ROW.rar to a folder and open flash tool extracted folder and run flash_tool.exe

2)On the flash tool, click Scatter-Loading button browse and then select file name MT6752_Android_scatter.txt, just find it on K50a40_S112_150610_ROW target_bin folder, then click open.

3)Now it will load the above file, make sure only recovery selected and select the Firmware Upgrade option.

4)In the menu Option tab, select Download and check DA DL All with Checksum.

5)Click Download button or hit F9

6)Completely turn off your phone and wait for about 10 sec (BUT DO NOT REMOVE BATTERY) and NOW connect it to PC using usb cable, this will start the flashing process on flash tool.

7)Wait till the Process completes (5-10mins) and a "Download ok" box will appear with a green tick. Disconnect the phone from cable. Done!

8)Then switch on your phone just wait, it will take some minutes for first boot and be patient.

You will see your device boot up like the first time you booted it up. Fresh as a new. It has a custom recovery installed so it advised to take a backup of the fresh system using TWRP incase you need it in future. Press and hold VolumeUp+VolumeDown+PowerButton to access recovery menu.

So now you have unbricked your phone and it's also in unroot condition. Follow the procedure and you'll be good.

Attention:

I'm not responsible for any damage that occurs to your smartphone, for committing install Stock ROM on your smartphone is very risky, if you have a doubt it better don't do it or give to someone who is more understand with this installing. Thanks.