Thanks for the github link I have been having a look through it.
The power LED (and processor) is powered from the Receiver. The battery power to the battleswitch only goes to the output, so don't worry about plugging that in for the moment.

From the code in the github repo it looks like:
- When you first turn the device on, you should get both LEDs turn on for one second, then turn off for one second. This shows everything has started up correctly in the processor.
- It will then flash the LEDs alternatively at a frequency of 10Hz until it is happy with the signal from the receiver.
- When it is happy with the signal, the LEDs will show what outputs are on.
- If, at any time it is not happy with the signal from the receiver, it will go back to flashing the LEDs alternatively.