ผมจะแฟลช Xperia Arc จาก 4.0.2.A.0.62 ให้เป็น 4.0.2.A.0.42 เพื่อรูทครับ
แต่แฟลชเท่าไหร่มันก็ขึ้น error แบบนี้ครับ

04/057/2555 12:57:03 – INFO – <- This level is successfully initialized
04/057/2555 12:57:03 – INFO – Flashtool Version 0.7.1.0 built on 2012-05-01 22:07:23
04/057/2555 12:57:03 – INFO – You can drag and drop ftf files here to start flashing them
04/057/2555 12:57:07 – INFO – List of connected devices (Device Id) :
04/057/2555 12:57:07 – INFO – List of ADB devices :
04/057/2555 12:57:07 – INFO – – none
04/057/2555 12:57:07 – INFO – List of fastboot devices :
04/057/2555 12:57:07 – INFO – – none
04/057/2555 12:57:08 – INFO – Device disconnected
04/057/2555 12:57:48 – INFO – Device connected with USB debugging off
04/057/2555 12:57:48 – INFO – For 2011 devices line, be sure you are not in MTP mode
04/057/2555 12:57:49 – INFO – Device connected with USB debugging on
04/057/2555 12:57:49 – INFO – Connected device : LT15
04/057/2555 12:57:49 – INFO – Installed version of busybox : N/A
04/057/2555 12:57:49 – INFO – Android version : 2.3.4 / kernel version : 2.6.32.9-perf
04/058/2555 12:58:00 – INFO – List of connected devices (Device Id) :
04/058/2555 12:58:00 – INFO – – USBVID_0FCE&PID_614F&MI_017&310B59E6&0&0001 Driver installed : true
04/058/2555 12:58:00 – INFO – – USBVID_0FCE&PID_614F&MI_007&310B59E6&0&0000 Driver installed : true
04/058/2555 12:58:00 – INFO – – USBVID_0FCE&PID_614F43423541314431505039 Driver installed : true
04/058/2555 12:58:00 – INFO – List of ADB devices :
04/058/2555 12:58:00 – INFO – – 43423541314431505039
04/058/2555 12:58:00 – INFO – List of fastboot devices :
04/058/2555 12:58:00 – INFO – – none
04/058/2555 12:58:13 – INFO – Selected LT15i_4.0.2.A.0.42_Generic Global.ftf
04/058/2555 12:58:13 – INFO – Flash canceled
04/059/2555 12:59:42 – INFO – Selected LT15i_4.0.2.A.0.42_Generic Global.ftf
04/059/2555 12:59:42 – INFO – Preparing files for flashing
04/059/2555 12:59:42 – INFO – Please connect your device into flashmode.
04/059/2555 12:59:47 – INFO – Device disconnected
04/000/2555 13:00:37 – INFO – Device connected in flash mode
04/000/2555 13:00:38 – INFO – Opening device for R/W
04/000/2555 13:00:38 – INFO – Reading device information
04/000/2555 13:00:38 – INFO – Phone ready for flashmode operations.
04/000/2555 13:00:38 – INFO – Start Flashing
04/000/2555 13:00:38 – INFO – Flashing loader
04/000/2555 13:00:38 – INFO – Ending flash session
04/000/2555 13:00:38 – ERROR – ERR_SEVERITY="MAJOR";ERR_CLASS="SECURITY_CLASS";ERR_DYNAMIC="SIN header verification failed"
04/000/2555 13:00:38 – INFO – Device connected in flash mode
04/000/2555 13:00:39 – INFO – Device disconnected

ตรงตัวแดงนั่นแหละครับ มันขึ้นแบบนี้ตลอดเลย ลองหลายรอบแล้วครับ ช่วยแนะนำที ขอบคุณครับ