Can you try the troubleshooting page and try and see if power is always connected? When in bootloader mode, some LEDs should always be lit up - so if they're not then something is wrong.
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.
Can you try the troubleshooting page and try and see if power is always connected? When in bootloader mode, some LEDs should always be lit up - so if they're not then something is wrong.