Install Official Android 4.0.4 ICS Update On Nexus S 4G

Step 1: Download the following necessary files:

• IMM26 Production Firmware
• Kernel For ICS Wimax IDK Files
• Odin

 Step 2: Download Odin and run .exe file
Step 3: Download and extract the firmwarefile.
Step 4: Open Odin, but be sure not to modify any of the defaults, and do not – under any circumstances – select EFS clear or you will wipe PRL.
 Step 5: Select the software files as follows:

Bootloader: SPH-D720-IMM26-BootLoader-signed.tar (checksum: 7d8b0ad9617b832eeac8786dac2305a9)
PDA: SPH-D720LE-IMM26-PDA Signed.tar (checksum: e3c8e116fbb8668bf3ad0d0cd8b16ed6)
Phone: SPH-D720LE-IMM26-Modem-Signed.tar (cheksum: c346cc28067305bec764f061d9a57098)

Step 6: Now you’ll be flashing via Fastboot. Here are the checksums For The IMG Files:

3d3128bc2b4e2243251892c36277dd87 boot.img
a4b95efbc4298105b52817104cb9d8e0 bootloader.img
a00bf94e614c1b61527491843b435a9e recovery.img
f813f065ed3ad0f22df2b9e6d44edeeb signed_radio.img
1d882334f0f4980984a43d67571d1ebf system.img
6a29adb1ec187b4e2eb61104e0fe2f26 userdata.img

If you followed the steps correctly, your Samsung-made Google Nexus S 4G will reboot into a leaked, official build IMM26 of Android 4.0.4 Ice Cream Sandwich.