I ordered a Sonoff S20 and want to flash new firmware on it. I have the Australian / New Zealand version and the PCB doesn't look the same as what I've seen on the web, and unfortunately it doesn't have any markings that label the pins where one would normally solder the header for uploading firmware.
This is the PCB that I have: https://imgur.com/a/FXh1h
Note that it appears to be the same as the one shown on the ITead web page for the S20 socket, seen here: http://sonoff.itead.cc/en/products/residential/s20-socket.
Can anyone tell me which pins are which? There also appear to be two different 4-pin blocks.