Datasheet

If the bootloader couldn't start, you will get a red NeoPixel LED.

That could mean that your USB cable is no good, it isn't connected to a computer, or maybe the drivers could not

enumerate. Try a new USB cable first. Then try another port on your computer!

Once the bootloader is running, check your computer. You should see a USB Disk drive...

https://learn.adafruit.com/adafruit-feather-m0-express-designed-for-circuit-python-

circuitpython

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