Web Serial isn't available in this browser.
Use a desktop version of Chrome, Edge, or Opera, connected to your device over USB.
(Firefox and Safari don't support Web Serial yet.)
1 Choose your board
2 Connect
Plug your device in via USB, then click Connect and pick its serial port from the browser dialog.
3 Flash
✓ Done
Firmware flashed successfully. The device is rebooting into Draftling. Files on the SD card are untouched.