Sometimes it is difficult to keep the switch pressed while powering / plugging in the micro USB connector. To make it work reliably, I plug the USB cable first to the Espruino Wifi, then press and hold the switch and plug the other end of the cable into the USB connector of my computer.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Sometimes it is difficult to keep the switch pressed while powering / plugging in the micro USB connector. To make it work reliably, I plug the USB cable first to the Espruino Wifi, then press and hold the switch and plug the other end of the cable into the USB connector of my computer.