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By MaxTR

I have 3 ESP8266 (1x Thing WRL-13231 and 2x Thing-Dev-V10)
with the Thing and one of the Thing-Dev I have no problems but one, it will not boot by power on
the arrangement of the two Thing-Dev are nearly the same

I used D4, D5, D12, D13, D16 for driving a relay all of them on the GPIO with a 1kOhm resistor to the base of a transistor

D2 an D14 as Input for announcing a state (Low 0V Hi 3V by optocoupler)

to the beginn I have had no problems, when power goes OFF and ON again but in the last, the ESP8266 will not start
when I take them from the board away, it start and I can put him to the board again and it's working

what can be the problem?

thank you for help