Why the headphone indicate light is on after turned off?
As the ANC function is independent from the headphone Bluetooth connection.
When you turn off B133 headphones by power button, the Bluetooth will be disconnected, but ANC won`t be turned off if it was turned on.
The headphones has 2 indicator lights, 1 for blue-tooth connection, 1 for ANC function, to turn off the headphones, you need to turn off by power button, but also turn off ANC mode.
The ANC indicator light will be still on, and working until you turn ANC OFF.