In my quick review of the Atreus here I mentioned being confused about the flashing procedure and ended up soft-bricking the device.
I seem to be able to flash the firmware with Chrysalis and edit the layers without much issue now, but on Arduino, despite holding down the bottom-left key through the entire flashing duration, I get the message:
Arduino: 1.8.13 (Linux), Board: “Keyboardio Atreus”
Sketch uses 21304 bytes (74%) of program storage space. Maximum is 28672 bytes.
Global variables use 919 bytes (35%) of dynamic memory, leaving 1641 bytes for local variables. Maximum is 2560 bytes.
An error occurred while uploading the sketch
avrdude: ser_open(): can’t open device “/dev/ttyACM0”: Device or resource busy