Circuit Playground Express Bootloader

The board needs the right type of firmware to execute the code properly
the board is either in

MAKECODE mode:

SINGLE-click the reset-button

or

CIRCUITPYTHON (or Arduino) mode:

DOUBLE-click the reset-button (neopixels turn green)

CPLAYBOOT mounts

download latest uf2 firmware from https://circuitpython.org/
> press “Downloads” and locate your board

(if your board misbehaves, it might need a new bootloader )