No offense, why would you every tell anyone who has no idea, to reparation their sd.It wipes data.
Answer to question
If your phone boots up saying "GALAXY S 4G" you aren't bricked. Also, If you wait long enough, the phone would turn on. Anyway, turn your phone off by pulling out the battery. First, press volume up and down together. Hold it. Then hit the power button for 4 seconds. Release the power button. After some time, you will be in recovery mode. (red with writing). Using the volume up and down buttons, navigate to the section that says voodoo lag fix. Press power button to click. Then disable voodoo lag fix by clicking disable and disable system lag fix by clicking disable. Now navigate to the "go back" button, and go back. click reboot system and it will work.