I’ve had them from several places and they all seem to be the same. They use the “RFX2401” amplifier with a non-standard layout.
The programming pads / 5v / 3v3 / Gnd are labeled on the PCB – but do note that the internal power supply isn’t isolating and indeed the 5v supply is at the live mains voltage. Hence if powered by the mains, the entire PCB and all the data lines are at mains voltage and very dangerous.
Attention! They must only be powered by the 5v/3v3 pads whilst programming / out of the case. Do not connect the high voltage wires.
Download the latest version of the configurable firmware here. Then adjust the settings.
The main page:
Status LED: P10
Output1: P07 GPIO Tri-state
Input1: P13 GPIO Pull-up
The Expert page:
RFX2401 TXEN:P12 RXEN:P14