[HELP]: Wrong u_boot into flash

[kader_73]

output help nand

7119 > help nand
nand info                  - show available NAND devices
nand device [dev]     - show or set current device
nand read[.jffs2]     - addr off|partition size
nand write[.jffs2]    - addr off|partition size - read/write `size' bytes starting
    at offset `off' to/from memory address `addr'
nand erase [clean] [off size] - erase `size' bytes from
    offset `off' (entire device if not specified)
nand bad - show bad blocks
nand dump[.oob] off - dump page
nand scrub - really clean NAND erasing bad blocks (UNSAFE)
nand markbad off - mark bad block at offset (UNSAFE)
nand biterr off - make a bit error at offset (UNSAFE)
nand lock [tight] [status] - bring nand to lock state or display locked pages
nand unlock [offset] [size] - unlock section

7119 >

output nand info

7119 > nand info

Device 0: NAND 256MiB 3,3V 8-bit, sector size 128 KiB
7119 >

output command :

7119 > usb reset
(Re)start USB...
USB:   scanning bus for devices... 3 USB Device(s) found
       scanning bus for storage devices... 1 Storage Device(s) found
7119 > fatload usb 0:1 80000000 mtd0
reading mtd0
.........................

262144 bytes read
7119 >

One more thing, I used this command "dd if=/dev/mtd0 of=/tmp/mtd0 bs=128k count=2" to save the file mtd0, while this was in a tutorial given for an hs7810 (NOR flash 32M) that I applied on my 7819 . I hope that the resulting file is correct. I'm afraid to screw up the u_boot and then find myself with a dead box !!