Dimensions - 125 x 63 x 8.7 mm
Weight - 117g
Display - 4.2 inches
Resolution - 854 x 480 px (~233ppi)
CPU - 1.4GHz
GPU - Adreno 205
Chip - Qualcomm Snapdragon S2
RAM � 512MB
Internal Memory � 1GB
MicroSD - Up to 32GB
Single SIM
GPRS - EDGE - HSPA - UMTS
Bluetooth � Version 4.0
WiFi - 802.11a - 802.11b - 802.11g - WiFi Hotspot - WiFi Direct
Primary Camera - 8 MP with LED Flash
Secondary Camera - No
Battery - 1500mAh
Learn how to unbrick/flash or upgrade this device using flashtool from here
Note
Follow the instructions on how to flash the device carefully from the link above
I will not take responsibility on whatever may happen to your device.
Make sure you are downloading the exact ROM of the device you want to flash because
Flashing a wrong rom will make the device completely dead
(can't power on, can't charge and will not be detected by a computer)
SONY XPERIA ARC S LT18i STOCK ROM/FIRMWARE
Android 4.0.4 Ice Cream Sandwich
LT18i_4.1.B.0.587
Size - 374MB
Android 2.3 Ginger Bread
LT18i_4.0.A.2.0.62
Size - 253MB
Get other sony xperia roms from here