1. Find a thing that fits in the hole on the bottom panel labeled "BOOT". It should be at least 2 cm long and if it's non-conductive, that's cooler than if it is. (A screw driver is ok, but a toothpick is cooler).
2. Plug the Round Robin into your computer with a USB cable.
3. With the power switch in the Off position, insert the thing from step 1 into the BOOT hole (lol). You're pressing a little button indoe, so you should feel a small click.
4. With the internal button held down, flip the power switch to On. The Round Robin should show up on your computer as a drive.
5. Drag the .uf2 file onto the root of this drive. The Round Robin should sense the file's presence and automatically update itself and restart.