How to fix bad sector on NAND Flash Memory

A week ago, I flashed my Nexus S 4g with a custom kernel (Matrix) and ROM (CWM9). On reboot, my NS4G always bootloops, stuck on bootloader loading screen, and never gets to the Android System. It had the same result when I tried to flash it back to a stock ROM. I removed the battery, put it again and tried to boot into recovery to use adb to check my SD card content with parted (I think there was a problem on partition). In parted I can reformat it using adb or recovery, but its content couldn't be changed. I think there was a problem with NAND flash. Is there any way that I could Reformat NAND flash to fresh state?