 any other power inputs)
   <li><b>Press and hold</b> the small white BOOTSEL button on top of the Pico
   <li>While <b>still holding</b> BOOTSEL, plug the USB cable back in
   <li>Release the BOOTSEL button
</ul>
<p>
   This will put the Pico into its Boot Loader mode.
   In this mode, the Pico appears on the Windows desktop as
   a generic USB thumb drive.  It's not <i>really</i> a thumb drive; it's
   just pretending to be one, as a convenient way to accept files for firmware
   installation.  You can in