Read here : Flash your phone and How to apply or remove patch using SETool 2 Lite - Top Sony Forums and use these files
K770_R8BC004_FS_S_ASIA_LEVAN_RED52
K770_R8BC004_MAIN_GENERIC_VI_RED52
HB1-06_Gen_CDA102568_110_R8A_GENERIC_S_ASIA_LEVAN
the most important part is the part 3, the unlock part, don't miss it