Error on rooting

[rvgeex]

Hi, I have a problem when I try to root the DGNWG05LM. After use the command setenv bootargs "${bootargs} single rw init=/bin/bash" && boot, I have a error message:

[    2.870402] VFS: Mounted root (ubifs filesystem) on device 0:14.
[    2.877693] devtmpfs: mounted
[    2.881892] Freeing unused kernel memory: 540K (80aa1000 - 80b28000)
bash: cannot set terminal process group (-1): Inappropriate ioctl for device
bash: no job control in this shell
bash-4.3#

If I don't use init=/bin/bash, the boot goes further but it doesn't work anymore

=> setenv bootargs "${bootargs} single rw" && boot

NAND read: device 0 offset 0x300000, size 0x700000
 7340032 bytes read: OK

NAND read: device 0 offset 0xa00000, size 0x100000
 1048576 bytes read: OK
Kernel image @ 0x80800000 [ 0x000000 - 0x617290 ]
## Flattened Device Tree blob at 83000000
   Booting using the fdt blob at 0x83000000

...

[    2.876859] devtmpfs: mounted
[    2.880976] Freeing unused kernel memory: 540K (80aa1000 - 80b28000)
INIT: version 2.88 booting
Starting udev
cmp: EOF on /etc/udev/cache.data
udev: Not using udev cache because of changes detected in the following files:
udev:     /proc/version /proc/cmdline /proc/devices
udev:     lib/udev/rules.d/* etc/udev/rules.d/*
udev: The udev cache will be regenerated. To identify the detected changes,
udev: compare the cached sysconf at   /etc/udev/cache.data
udev: against the current sysconf at  /dev/shm/udev.cache
[    3.869683] udevd[105]: starting version 3.1.5
Populating dev cache
Give root password for maintenance
(or press Control-D to continue):

Could you help me?

[devbis]

And what blocks you from setting a root password in bash?

[rvgeex]

And what blocks you from setting a root password in bash?

If I don't use init=/bin/bash, it asks me to enter a password (which I don't know) not to set a new one. If I press Control-D, it ask me again the password

[devbis]

You must run with init=/bin/bash, your gif shows you booted normally.

[rvgeex]

You must run with init=/bin/bash, your gif shows you booted normally.

But after the boot, I can't write anything

[devbis]

It could be a problem with your usb-serial convertor, computer, or OS.