Use a USB-C cable to plug your device into your computer. The TRMNL branded cable works great if you have one.
Step 3 - Enter 'Flashing mode'
Select a device model above for instructions.
Turn off the device by flipping the power switch to 'OFF'
While pressing down on the circular button, flip the power switch to 'ON'
Let go of the circular button
If you're running X4 default firmware or Crosspoint, wake up the device.
If you're already running TRMNL firmware, hold the X4 reset button for 3 seconds.
Note: The X4 only remains in a "flashing mode" state for a couple seconds. Follow the prompts in Step 4 immediately after holding the reset button or you'll need to retry.
Step 4 - Flash firmware
Click the 'Connect' button below
Select 'USB JTAG/serial...' from the list
Select 'Install' from the popup menu
Wait for the device to install the firmware (this may take a minute or two)
You should see a confirmation message within the popup menu
Step 5 - Restart your device
Turn the device off by flipping the power switch to 'OFF'
Wait approximately 15 seconds
Flip the power switch to 'ON'
Troubleshooting
If you get an error "Failed to execute 'open' on 'SerialPort' during Step 4:
your USB-C cable might only be capable of charging (not data transfer)
your device may not yet be in "flashing mode."
Repeat Step 2 or see this guide for additional options.