Os dejo el log, la ftf a instalar es esta 12.1.A.1.205_ES :
03/015/2014 20:15:53 - INFO - Device connected in flash mode
03/015/2014 20:15:53 - INFO - Opening device for R/W
03/015/2014 20:15:53 - INFO - Reading device information
03/015/2014 20:15:53 - INFO - Phone ready for flashmode operations.
03/015/2014 20:15:53 - INFO - Current device : C5303 - YT910NNRNB - 1272-7157_R7B - 1269-3538_12.1.A.1.205 - ORANGE-LTE_12.1.A.1.205
03/015/2014 20:15:53 - INFO - Start Flashing
03/015/2014 20:15:53 - INFO - Processing loader.sin
03/015/2014 20:15:53 - INFO - Checking header
03/015/2014 20:15:53 - INFO - Flashing data
03/015/2014 20:15:53 - INFO - Processing of loader.sin finished.
03/015/2014 20:15:54 - INFO - Loader : S1_Root_7054 - Version : R5G006 / Boot version : R11B023 / Bootloader status : NOT_ROOTABLE
03/015/2014 20:15:56 - INFO - Processing partition-image.sin
03/015/2014 20:15:56 - INFO - Checking header
03/015/2014 20:15:56 - INFO - Flashing data
03/015/2014 20:15:59 - INFO - Processing of partition-image.sin finished.
03/015/2014 20:15:59 - INFO - No bootdelivery to send
03/015/2014 20:15:59 - INFO - Processing kernel.sin
03/015/2014 20:15:59 - INFO - Checking header
03/015/2014 20:15:59 - INFO - Flashing data
03/016/2014 20:16:05 - INFO - Processing of kernel.sin finished.
03/016/2014 20:16:05 - INFO - Processing fotakernel.sin
03/016/2014 20:16:05 - INFO - Checking header
03/016/2014 20:16:05 - INFO - Flashing data
03/016/2014 20:16:09 - INFO - Processing of fotakernel.sin finished.
03/016/2014 20:16:09 - INFO - Processing amss_fs_2.sin
03/016/2014 20:16:09 - INFO - Checking header
03/016/2014 20:16:09 - INFO - Flashing data
03/016/2014 20:16:10 - INFO - Processing of amss_fs_2.sin finished.
03/016/2014 20:16:10 - INFO - Processing amss_fs_1.sin
03/016/2014 20:16:10 - INFO - Checking header
03/016/2014 20:16:10 - INFO - Flashing data
03/016/2014 20:16:11 - INFO - Processing of amss_fs_1.sin finished.
03/016/2014 20:16:11 - INFO - Processing amss_fsg.sin
03/016/2014 20:16:11 - INFO - Checking header
03/016/2014 20:16:12 - INFO - Flashing data
03/016/2014 20:16:13 - INFO - Processing of amss_fsg.sin finished.
03/016/2014 20:16:13 - INFO - Processing apps_log.sin
03/016/2014 20:16:13 - INFO - Checking header
03/016/2014 20:16:13 - INFO - Flashing data
03/016/2014 20:16:14 - INFO - Processing of apps_log.sin finished.
03/016/2014 20:16:14 - INFO - Processing cache.sin
03/016/2014 20:16:14 - INFO - Checking header
03/016/2014 20:16:15 - INFO - Flashing data
03/016/2014 20:16:19 - INFO - Processing of cache.sin finished.
03/016/2014 20:16:19 - INFO - Processing system.sin
03/016/2014 20:16:19 - INFO - Checking header
03/016/2014 20:16:19 - INFO - Flashing data
03/019/2014 20:19:01 - ERROR - Processing of system.sin finished with errors.
03/019/2014 20:19:01 - INFO - Ending flash session
03/019/2014 20:19:01 - ERROR - 995 : La operación de E/S se anuló por una salida de subproceso o por una solicitud de aplicación.
03/019/2014 20:19:01 - ERROR - Error flashing. Aborted
03/019/2014 20:19:01 - INFO - Device disconnected
03/019/2014 20:19:02 - INFO - Device connected with USB debugging off
03/019/2014 20:19:02 - INFO - For 2011 devices line, be sure you are not in MTP mode
03/019/2014 20:19:06 - INFO - Device disconnected
Con el Xperia SP soy novato y no le hice boot unlock