@Vukan-Vuk Yes, @CAP-33 is correct - you can not turn off the POWER LED of Power Dock without some hardware action / modification.
The expled tool - originally - is able to control the RGB LED of an Expansion Dock via GPIO15, 16, 17.
See also Expansion Dock > Using the Dock > Controlling the RGB LED
Power Dock 2 has a virtual PB (PushButton) that we can push with the power-dock2 utility via GPIO16 (or unintentionally because GPIO16 is floating by default ;-).
See also Checking the Battery Level
Up to now I thought that PB is effective only if a battery is connected to the board.
It seems you have found a creative way when you are keep pushing it with an expled command - theoretically 200 times per second ;-).
You should try to stop the PWM signal on GPIO16 with fast-gpio set-input 16 - this was the default state of GPIO16.
Using the Omega’s GPIOs > Fast-GPIO > Generating a PWM signal on a GPIO:
Generate a software-based Pulse Width Modulated (PWM) signal on a selected pin. Specify the desired duty cycle and frequency of the PWM signal.
fast-gpio pwm <gpio> <freq in Hz> <duty cycle percentage>
This will launch a background process that will generate the PWM signal.
To stop the PWM signal, set the GPIO’s value:
fast-gpio <gpio> 0
fast-gpio set <gpio> 0 - set the output LOW (if there's an active LOW LED then it will be ON) or
fast-gpio set <gpio> 1 - set the output HIGH (if there's an active LOW LED then it will be OFF).
Are these fast-gpio pwm ... processes running in the background really?