That gives the error - "hexdump: /dev/mtdblock3: No such device or address"
I can see mtdblock3 in the /dev directory but can't do anything with it.
So you can see the existence of the device node (
/dev/mtdblock3) but do not have any utility available to check its contents. Hmm . . .
Does your ZyXEL VMGxxxx device have the
cat utility available? Try
cat /etc/passwd and see what is displayed. If there is no error, you could try
cat /dev/mtdblock3 and see what is produced.
Note: On ZyXEL VMGxxxx devices, the contents of the /dev/mtdblock3 node is predominantly ASCII (or UTF-8), with just a few binary characters at the beginning. So it would be reasonable to invoke a cat of the device.
If the ROM-D
has not been cleared, you will see a mass of readable ASCII (or UTF-8) text displayed.
If the ROM-D
has been cleared, you will see something like that shown in the following attachment --