read here : Flash K800 CID53 with K810 software CID53 (for begginers) - Top Sony Forums but use files only for K800, you can use the files below
K800_R8BF003_MAIN_GENERIC_WI_RED53
K800_R8BF003_FS_APAC_RED53
HB1-06_Gen_CDA102568_101_R8A_GENERIC_APAC