If you android phone's not turning on and displaying the error message "Custom Binary blocked by FRP Lock", don't panic, the solution is right in this article.
Samsung Kies 3
Click here to download it
After download Samsung Kies 3, Install it
Open It
Click on Tools and choose Firmware Upgrade and Initialisation

Enter Details
Just type in the Model Name of the phone and press Enter. Now type in the Serial Number.
After entering the required details, just click Ok. You may be prompted some warnings. Just Click Ok.
You should now be seeing a window like this but with your appropriate details:

Go into Download Mode
Press Volume Down, Power Button and Home Button together, until you see a Warning Sign. You're now in Download Mode. Now press Volume Up to continue.
Connect your phone to Laptop/PC via USB cable and Click on Start Upgrade on Samsung Kies 3.
Note: This was tested on Samsung J7 and worked perfectly fine.
You'll need:
Steps

You can get Model Name and Serial Number by removing battery, It should be written on the phone behind the battery.
After entering the required details, just click Ok. You may be prompted some warnings. Just Click Ok.
You should now be seeing a window like this but with your appropriate details:
To be able to Start the Upgrade, you'll need to go into Download Mode in your Android Device.
You're Done!!
You just need to wait.
Note: This process might take some time to complete, so you'll need to be patient.