1. Downgrade to 14.1.G.1.534 ftf using latest flashtool version.
But from where should I download .534 ftf ...http://forum.xda-developers.com/devd...2083#downloads ( the file here is for C6903..where to find c6902 ftf. ?? ) or http://forum.xda-developers.com/show....php?t=2469191
2. Install XZDualRecovery 2.7.90 BETA or newer.
3. Download C6902_14.3.A.0.757.flashable.zip and C6902_14.3.A.0.757_Stripped.ftf and follow the instructions to install them ( as provided by NUT at http://forum.xda-developers.com/show....php?t=2711982)
I also have one question: If I have to unlock boot-loader (& hence back up TA first), Is it possible to do so after flashing above mentioned .zip and stripped.ftf files. ??