The button is designed to rectify the detected cell numbers of your XT60 battery manually when the detected number shown on the LED is wrong. 

If the detection result is wrong, you can short press the button to swtich from 2S-6S or disable the cut-off voltage function.

But the software detection accuracy is pretty good, so in most of the case you won't need to press the button.

In case you are confused with the meaning of figures on the LED, we list the detailed examples below.

Power the Thor via XT60 Port 

Suppose you are charging the Thor with a 3S battery, whose voltage is 12V. 

Situation A:  Your 3S Battery Charging the Thor

You might see "00.8"(really small amount of voltage) "UP" shown in cycle as soon as you plug the battery to the adaptor.

Don't worry, it takes time for initialization.

After initialization, the cell numbers and the detected voltage would be shown in cycle.   

So "3" and "12" would be shown in cycle on LED.

And the detected real-time voltage of your 3s battery would be shown during the charging process

Situation B: Your 3S Battery Reached its Cut-off Voltage

When the 3S battery reached the cut-off voltage 11.1V (3.7V x cell numbers), the "3" and "OFF" would be shown on LED and it would stop power the Thor.

Situation C: Disable the Cut-off Voltage Function

You can short press the button and when the "ON" is shown, it means the cut-off voltage function is now disabled.

The voltage and "on" will be shown in cycle. 

Power the Thor via USB Type-C Port

Note: the Thor adaptor only supports Quick Charge 12V, pleasae check if your powerbank is capable of outputing Quick Charge 12V before you buy this unit.

Situation in which your powerbank supports 12V Quick Charge

"ERR" "5" "UP" will be shown on LED in cycle after you connect the adaptor with the powerbank. Please don'y worry, this is not a bug. It takes a few seconds for the powerbank and the adaptor to establish communication as the powerbank outputs 5V by default while the Thor adaptor needs 12V to work properly. 

Once the communication is successfully established, the "ERR" "5" "UP" will disappear.

And "12" "UC" will be displayed in cycle after the communication is successfully completed.

Situation in which your powerbank doesn't support 12V Quick Charge

"ERR" "5" will be shown in cycle all the time and the Thor can not be powered.