I got this working on a Dell Precision M4700 laptop. The backlight turns off completely for me after 120 seconds and turns it back on with when any key is pressed. It took me a while to piece together how to do it so I’ll summarize the steps:
Step 1: On the laptop itself (not in the SSH hass add-on), type “login” and press enter i.e.
ha > login. This didn’t work immediately for me but after a few tries, it worked. You should see a new line with
# if it worked.
Step 2: Open file to edit with vim.
# vi /mnt/boot/EFI/BOOT/grub.cfg
Step 3: Find the line starting with “default_cmdline=” and add “consoleblank=120” at the end of the line but before the double-quotes at the end of the line.
default_cmdline="rootwait <other stuff> consoleblank=120"
Note: To insert stuff in vim, press ‘i’ to enable insert mode. Edit the file. Then press ‘esc’ to exit insert mode. Then type
:wq <ENTER> to save and exit vim.
Step 4: restart the laptop