[Tutorial] - Fixing a bricked system

[TheStranger]

Code:

/ # mkdir /tmp/sd
/ # mount /dev/sdcardb1 /tmp/sd
/ # ls /tmp/sd
LLN                        flash4                     original_backup.bin
S3s_DE_v74.50312-MOD.bin   flash4-innotab3            sdcarda6_backup.bin
System Volume Information  fonts
execute.ita                my_Run
/ # dd if=/tmp/sd/original_backup.bin of=/dev/sdcarda6
53816+0 records in
53816+0 records out
27553792 bytes (26.3MB) copied, 17.819052 seconds, 1.5MB/s
/ # app_destroyer.x -f
[  599.020000] SQUASHFS error: zlib_inflate error, data probably corrupt
[  599.030000] SQUASHFS error: squashfs_read_data failed to read block 0x1a06461
[  599.040000] SQUASHFS error: Unable to read fragment cache entry [1a06461]
[  599.040000] SQUASHFS error: Unable to read page, block 1a06461, size c512
[  599.050000] SQUASHFS error: Unable to read fragment cache entry [1a06461]
[  599.060000] SQUASHFS error: Unable to read page, block 1a06461, size c512
[  599.060000] SQUASHFS error: Unable to read fragment cache entry [1a06461]
[  599.070000] SQUASHFS error: Unable to read page, block 1a06461, size c512
-/bin/sh: app_destroyer.x: Input/output error

Now i copy my original firmware (the first befor i flash with a mod) as original_backup.bin to the micro-sd and did all steps to fastboot kill. Get the same errors (see above).

What did i wrong?