Sorry,
it was months ago.
I succeded flashing and operating it, but then the prototype was left in a corner.
I remember it was not immediate, and I troubleshooted somewhere, but unfortunately I did not took notes of it.
I can only suggest to look for solution for this specific case.
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.
Also, do you remember which Espruino Firmware you managed to get the whole thing to work with?