When the LEDs are pulsing red and green it's in bootloader mode. So if you're just trying to connect it to write code to it you need to connect it to USB without holding the button down so no LEDs are lit.
But you should still be able to connect... just not get any response from it.
So that could be an issue, but if you're not seeing Web Serial maybe you need to go to chrome://flags and enable Experimental Web Platform features? I think they get enabled on Windows/etc by default but on Linux it might need toggling.
Also what's your Chrome/Chromium version? Are you definitely up to date?
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.
When the LEDs are pulsing red and green it's in bootloader mode. So if you're just trying to connect it to write code to it you need to connect it to USB without holding the button down so no LEDs are lit.
But you should still be able to connect... just not get any response from it.
So that could be an issue, but if you're not seeing
Web Serial
maybe you need to go to chrome://flags and enableExperimental Web Platform features
? I think they get enabled on Windows/etc by default but on Linux it might need toggling.Also what's your Chrome/Chromium version? Are you definitely up to date?