Say, you’re starting your electronics journey with a few projects in mind. You have an ESP8266 board like the Wemos D1, a Li-Ion battery, you want to build a small battery-powered sensor that ...

[Pete] was building a hot tub controller, using a WEMOS board based on the venerable ESP8266. After assembly, the board was plugged into USB and [Pete] hit the flash button. No dice. Investigation ...