[Q] no service after samsung s3 firmware update

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http://forum.xda-developers.com – Hi, I have a stock samsung galaxy s3 phone and i heard google now is an amazing feature so i was tempted to upgrade to jelly bean and i used odin to flash my s3 with jelly bean available on sammobile but it came up without network service. i then tried to flash it to stock firmware but after repeated attemps i could not get network service. tired and without sleep i finally handed it to samsung service centre. Now, i would like to know why this happened and will it get fixed or have i permanently broken something?? (HowTos)