Which IDE are you using? The Chrome App, or espruino.com/ide ?
Had you connected a different device to the IDE between times? If you don't connect outside of bootloader mode first then the IDE doesn't know what type of device it should be using.
It might be worth restarting your PC and trying again, just in case windows has got confused and thinks some other application is using the COM port.
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.
Sorry for the delay, I was away last week.
Which IDE are you using? The Chrome App, or espruino.com/ide ?
Had you connected a different device to the IDE between times? If you don't connect outside of bootloader mode first then the IDE doesn't know what type of device it should be using.
It might be worth restarting your PC and trying again, just in case windows has got confused and thinks some other application is using the COM port.