What the hell are you doing? Who told you to flash .514? It do not exist. Download from HERE the C6902 14.1.G.2.257 Commercial/Journalist 1277-1348_R1A and flash it on your phone. Turn on your phone and check if everything is ok, switch it off and hold volume down and connect in flashmode, then Downgrade again to C6902 14.1.G.1.534 Generic TW, Root this Firmware with Bin4ry Application and when you are rooted then follow the instruction to update to .290 from HERE, then update again to .136 from HERE. Read carefully all the instructions. This method is for Locked Bootloader and if you do all correctly you will have .136 fully rooted.