Android hdmi CEC commands error sys/class/cec/cmd not found why?

Question

I have amlogic tv BOX connected to my tv, i am trying to send CEC commands to the tv using HDMI cec commands

the HDMI CEC settings is enabled in TV side (all is turned on)

i follow the steps below:

1. run cmd and go to ADB
2. run adb connect 10.x.x.x ip address of tv box
3. run adb shell
4. run su for administrating
5. trying to run this command to turn off the tv #echo 0x40 0x04 > /sys/class/cec/cmd

the problem is i receive error : can't create /sys/class/cec/cmd not such file or directory

i am confusing how to check what files exists to run these CEC commands? and why i am getting this error?