Clean OS (Debian), OpenMediaVault and other "firmwares"

Hi,
i’m not sure if i got the howto right. I have a WDMyCloud-Gen2 with 6Tb and would like to install Debian with OMV on it.

The first part of the howto:

======= FW SETUP =======
Copy uImage, uRamdisk and rootfs-jessie.tar.xz to /boot/boot (Overwrite all)
Reboot
Connect via telnet
Repart HDD (Skip 3rd partition):
parted /dev/sda
rm 1
rm 2
rm 4
rm 5
rm 6
rm 7
mkpart primary 0% 1G
q
mkfs.ext4 /dev/sda1

Bevor doing that i tried if ssh and telnet to see if it works. I can ssh to it, but telnet does not work, i only get an “connection refuesed”.
I can’t figure out how to get telent to work on it.

Can somebody help me out please.