QUOTE(Wompa164 @ Jun 2 2010, 08:30 PM)

You don't need to manually remap those blocks. Any block after 0xFFF (so, 0x1000 and onward) on 256/512mb NANDs falls into the extended storage area and are automatically flagged as bad by the system, no manual remapping required.
ok i see thx well when i flashed Xell to the xbox it did not boot up and i also tried XBR but it still did not want to boot up?? what should i do?