binwalk -e original_fw.bin cd _original_fw.bin.extracted ls -la Look for a squashfs root and a kernel image. For the zsz53rla81, expect an offset at 0x200000 to 0x280000 . Extract the U-Boot header:
sudo mksquashfs /tmp/zsz_root new_root.squashfs -comp xz -b 256k The zsz53rla81 bootloader uses a non-standard header. Use a hex editor to copy the original 256-byte header from the donor firmware and paste it into your new file, then update the image_size field at offset 0x08 (little-endian). Recalculate the CRC: zsz53rla81 firmware repack upd
cat /proc/version # Check kernel build date md5sum /dev/mtdblock2 # Compare to your repack checksum binwalk -e original_fw
tftp 0x80000000 zsz53rla81_repacked_v2.bin erase 0x9f020000 +0x7c0000 cp.b 0x80000000 0x9f020000 0x7c0000 bootm After a successful zsz53rla81 firmware repack upd , verify integrity: zsz53rla81 firmware repack upd