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1. Firstly your computer translates double dashes into single long dashes. the dashes should be double dashes (--) for options such as--offset,--port, etc. The command should be:

   bossac -e -w --offset=0x16000 --port=usbmodem14201 -i -d -U -R file.bin

but I can see that your computer translated these-- to those— ?

2. Before you try to upload code confirm that the board is recognized by the system using thels command:

   ls /dev/cu.*

   This should list all serial devices and you should see something like/dev/cu.usbmodem14201 in the list if your board is connected.

3. Ensure that you have the necessary permissions to access the serial port. You can try running thebossac command withsudo to run it as the superuser:

   sudo bossac -e -w --offset=0x16000 --port=usbmodem14201 -i -d -U -R file.bin

4. Instead of just the port nameusbmodem14201, you might need to use the full path like/dev/cu.usbmodem14201:

   bossac -e -w --offset=0x16000 --port=/dev/cu.usbmodem14201 -i -d -U -R file.bin

5. Check that the Arduino Nano 33 BLE is in the bootloader mode. Typically, this can be achieved by double pressing the reset button. When it's in bootloader mode, the board might appear on a different port. Check the ports again withls /dev/cu.* after you double press the reset button.

If you try all those and still it doesn't work maybe you should try installing latest drivers or check compatibility. Anyways, good luck.

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