Check out the video tutorial https://www.youtube.com/watch?v=WDXKeTOK-Fo
If the above tutorial doesn't work try the following steps:
1) install KIES 3. DO NOT PLUG IN PHONE
2) go to tools -> firmware upgrade and initialisation in KIES
3) device id = (-----) ; serial number is under battery
4) allow KIES to download the firmware
5) place phone in ODIN mode/Emergency Download Mode (hold VOL DWN and HOME while powering on ) then plug in phone to computer via USB
6) allow KIES to send image to phone. Have some ice cream and egg rolls and do not touch anything.
7) After the phone restarts, it will take you through initial set up.
Let us know if it helped.