Second, for future explorers down this rabbit hole. This thread more or less has everything needed to get running. Either through the above mentioned MCU flash, or a bunch of different modifications to the board. Its all in here, you'll just need to read through this several times.
I have tried to document this https://github.com/cgmckeever/arduino-sketch/tree/master/esp-alexa-relay/relay-a#board-versions. Hopefully it helps as a good jump off point.