I have my program working nicely on a Sonoff POW. I can browse to its web page to configure it etc etc, all nice, BUT - only when its powered 3V from the serial header. As soon as I disconnect the header and connect to 240V, nothing works, all I get is the LED blinks every 8 seconds or so. I can flash it with the Tasmota image and it works fine when powered by 240V which suggests the hardware is OK. I have a second Sonoff POW that behaves the same way too. Can anyone suggest what might account for this strangeness?