Blackberry OS 10.3.1 upgrade has been available since February 2015
thou many can't upgrade to the new operating system (OS) maybe because
he/she is scared of doing it without the help of an Engineer.
Some are scared so that to upgrade over the air (OTA) due to fear of lossing
power supply along the upgrade which could become a problem during installation.

Requirements

Blackberry 10 Device
Micro USB Cable
Sachesi Software

How To Update Your BlackBerry 10 With Pc

Connect your device to your Pc with your USB Cable

Launch Sachesi.exe

Search for available OS updates by other carriers. Enter your country and
carrier codes under "Whitelist Settings" section

Download the updates and install

Visit the link below for detailed information and download link for the software.

http://www.sanxynet.com/2015/07/how-to-upgradeupdate-your-blackberry-10.html?m=1