my sony xperia t keeps on and off in flash mode

I'm trying to install a stock rom with flashtool, everything is good until it tells me to hold the vol- and plug the cable it runs the flash and it just disconnects after a few seconds.
Here is the flash log:
1/033/2015 22:33:31 - INFO - Device connected in flash mode
21/033/2015 22:33:32 - INFO - Device disconnected
21/033/2015 22:33:34 - INFO - Device connected in flash mode
21/034/2015 22:34:16 - INFO - Device disconnected
21/034/2015 22:34:29 - INFO - Selected Bundle for Sony Xperia T (LT30p). FW release : 9.2.A.1.199. Customization : Customized CE4
21/034/2015 22:34:29 - INFO - Preparing files for flashing
21/034/2015 22:34:40 - INFO - Please connect your device into flashmode.
21/034/2015 22:34:54 - INFO - Device connected in flash mode
21/034/2015 22:34:54 - INFO - Opening device for R/W
21/034/2015 22:34:54 - INFO - Reading device information
21/034/2015 22:34:54 - INFO - Phone ready for flashmode operations.
21/034/2015 22:34:54 - INFO - Opening TA partition 2
21/034/2015 22:34:54 - INFO - Current device : LT30p - CB51234S4F - 1269-9854_R1I - 1262-6309_9.1.A.1.141 - GLOBAL-HSPA_9.1.A.1.141
21/034/2015 22:34:54 - INFO - Closing TA partition
21/034/2015 22:34:54 - INFO - Start Flashing
21/034/2015 22:34:54 - INFO - Processing loader.sin
21/034/2015 22:34:54 - INFO - Checking header
21/034/2015 22:34:54 - INFO - Flashing data
21/034/2015 22:34:55 - INFO - Loader : S1_Root_7054 - Version : R5F001 / Boot version : R10AM009 / Bootloader status : ROOTABLE
21/034/2015 22:34:55 - INFO - Max packet size set to 65536
21/034/2015 22:34:56 - INFO - No flash script found. Using 0.9.18 flash engine
21/034/2015 22:34:56 - INFO - Opening TA partition 2
21/034/2015 22:34:56 - INFO - Writing TA unit 00002774. Value : [01]
21/034/2015 22:34:56 - INFO - Closing TA partition
21/034/2015 22:34:56 - INFO - Processing partition.sin
21/034/2015 22:34:56 - INFO - Checking header
21/034/2015 22:34:56 - INFO - Flashing data
21/034/2015 22:34:56 - INFO - Opening TA partition 2
21/034/2015 22:34:56 - INFO - Processing boot.sin
21/034/2015 22:34:56 - INFO - Checking header
21/034/2015 22:34:57 - INFO - Flashing data
21/034/2015 22:34:57 - INFO - Closing TA partition
21/034/2015 22:34:57 - INFO - Opening TA partition 2
21/034/2015 22:34:57 - INFO - Processing amss_fsg.sin
21/034/2015 22:34:57 - INFO - Checking header
21/034/2015 22:34:57 - INFO - Flashing data
21/034/2015 22:34:58 - INFO - Processing amss_fs_1.sin
21/034/2015 22:34:58 - INFO - Checking header
21/034/2015 22:34:58 - INFO - Flashing data
21/034/2015 22:34:59 - INFO - Processing amss_fs_2.sin
21/034/2015 22:34:59 - INFO - Checking header
21/034/2015 22:34:59 - INFO - Flashing data
21/034/2015 22:34:59 - INFO - Processing apps_log.sin
21/034/2015 22:34:59 - INFO - Checking header
21/034/2015 22:34:59 - INFO - Flashing data
21/035/2015 22:35:01 - INFO - Processing cache.sin
21/035/2015 22:35:01 - INFO - Checking header
21/035/2015 22:35:01 - INFO - Flashing data
21/035/2015 22:35:03 - INFO - Processing fotakernel.sin
21/035/2015 22:35:03 - INFO - Checking header
21/035/2015 22:35:03 - INFO - Flashing data
21/035/2015 22:35:07 - INFO - Processing kernel.sin
21/035/2015 22:35:07 - INFO - Checking header
21/035/2015 22:35:07 - INFO - Flashing data
21/035/2015 22:35:11 - INFO - Closing TA partition
21/035/2015 22:35:11 - INFO - Opening TA partition 2
21/035/2015 22:35:11 - INFO - Processing system.sin
21/035/2015 22:35:11 - INFO - Checking header
21/035/2015 22:35:12 - ERROR - Processing of system.sin finished with errors.
21/035/2015 22:35:12 - INFO - Ending flash session
21/035/2015 22:35:12 - ERROR -
21/035/2015 22:35:12 - ERROR - Error flashing. Aborted
21/035/2015 22:35:12 - INFO - Flashing finished.
21/035/2015 22:35:12 - INFO - Please unplug and start your phone
21/035/2015 22:35:12 - INFO - For flashtool, Unknown Sources and Debugging must be checked in phone settings
21/035/2015 22:35:12 - INFO - Device connected in flash mode
21/035/2015 22:35:13 - INFO - Device disconnected
21/035/2015 22:35:15 - INFO - Device connected in flash mode
how can I make my phone stop switching constantly?