About this component
With the button held while USB is connected, the Pico appears as a mass-storage drive and accepts a .uf2 firmware file; the bootloader is in ROM, so it always works if the hardware is sound. Test point TP6 does the same job if the button is broken: short it low while powering up.
What it does on this board
Held at power-up to enter USB mass-storage bootloader.
Pinout & readings
No pinout or reference readings yet — these show what each pin does and what a healthy part should measure.