...weird... I just had recently weird behavior in my Web IDE on OSX... but shutting down and restarting helped and I could re-flash the firmware. You obviously found the sweet spot of how long to hold the button when powering Espruino on in in order to get it into the re-flash mode (alternate pulsing of LEDs). Watch the progress bars... if they do not move smothly or too slow or are stuttering, something if of the tracks.USB cables are not all at their best and some iffy connection can cause weird effect. Check wires, cables... and just restart.
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.
...weird... I just had recently weird behavior in my Web IDE on OSX... but shutting down and restarting helped and I could re-flash the firmware. You obviously found the sweet spot of how long to hold the button when powering Espruino on in in order to get it into the re-flash mode (alternate pulsing of LEDs). Watch the progress bars... if they do not move smothly or too slow or are stuttering, something if of the tracks.USB cables are not all at their best and some iffy connection can cause weird effect. Check wires, cables... and just restart.