Upload is possible only once

[DavidMenting]

I'm using the ArduinoDE to upload a Blink program to the Seeed Arch Mix.

This is only possible on a freshly erased device with a fresly burnt bootloader. As soon as the sketch has been uploaded it the Arch Mix will no longer accept new sketches. It then needs a new mass erase (via SWD) and re-upload of bootloader.hex

Software/hardware used:
Arduino (Teensyduino) IDE 1.8.19
MacBook M1

[DavidMenting]

So I found out the Arch Mix doesn't enter the bootloader automatically. You need to press RESET and SW2, keep SW2 pressed while releasing RESET and waiting for the led to turn blue. This is not mentioned anywhere in the documentation.

I'd say this issue can be closed but would highly recommend adding the required sequence to the Arch Mix' documentation.