Welcome to Oseriz Support Center.

Press and hold the Light On/Off button to turn on the LED light. To change the mode, simply press the Light On/Off button again. 

There are two frequency which you can choose 50Hz and 60Hz. 
Step 1: Power on the AC Output. Press and hold the AC Output power button till the display turn on.
Step 2: Once the display is on, short press 3 times on the AC Output power button and it will change the power frequency.