I fully realize this is a user error issue, but I think a minor assembly instruction change can avoid this in the future.
I was showing my Wemos clock to my grandson, and the display board got accidentally plugged in backwards, and the clock won't display. This is possible because both J1 and J2 are symmetrical 10-pin connectors. On my clock, the main board has 10-pin sockets, and the display board has 10-pin headers.
I suggest changing the manual to have one 10-pin socket installed on the main board, and the mating 10-pin header installed on the display board. Then for the other pair, have the 10-pin header installed on the main board, and the 10-pin socket installed on the display board. This way, if the board is reverse, it won't install because it is socket-socket and pin-pin.
In future designs, you may want to change the headers so they are not symmetrical. For example make one a dual pin header, or maybe split one side in half with a gap so the display board cannot be installed if reversed.
Have to start debugging the clock now. When plugged in, all 4 leds are white, all nixies/neons are blank, and the ESP8266 board does not respond via the web. After checking power supplys I plan on trying to re-program the ESP, and maybe swap some of the socketted chips before looking at things like the optoisolators.
It's a good point: I have myself plugged in a few times incorrectly but I've never had it blow anything, It sounds like the Wemos has taken a dive, or the power supply has failed. Try taking the Wemos off and powering via a USB cable. It the blue LED flashes and it starts to react to web requests, then we know that it's likely the power supply part of the bard.
I like the idea of putting alternate pins/sockets, so that each board has one male and one female connector. I just have to make it so that the female one is the one that holds the power connections, and the male one is the one that controls the cathodes. In fact that is by far the best design, and this would protect the board well.
Thanks for the thought, It's a good one.
If there are any parts that you need, just let me know.
I wouldn't call it fragile. I don't know which of the boards we're talking about. Just out of curiosity I've taken a look into the schematics of the D1 mini and mini lite boards and the datasheet of the LDO. Given the absolute maximum ratings of the LDO both board designs ignore even basic design rules, so you should NEVER EVER plugin a live PSU...