No soldering for this first step…

Plug a quick-connect wire set into each of the four buttons.

There’s no specific polarity to these…either wire can go to either pin.

On the back of the PiTFT, near the GPIO pins, are two pads labeled “#18” with a narrow PCB trace between them.

Using a hobby knife or pointed file, scrape between the two pads to cut this trace. (It’s OK — if you ever need this back, a blob of solder between the pads will make the connection again.)

This makes sure the backlight stays on at full brightness. RetroPie otherwise has a tendency to make things dim and muddy.

The analog thumb joystick board has a 5-pin header and quite a few pins on the stick component itself. Some of the pins may be a little bent from shipping and need to be nudged into place. The “hat” simply presses into place.

Install a 5-pin header from below, so the pins are pointing “back” as shown here.

Make sure all your solder connections are smooth and clean, like tiny Hershey’s Kisses®. There should be no solder balls or bridges, no gaps between pins and their corresponding pads.

Three components are soldered to the Arcade Bonnet board:

• A 2-pin screw terminal goes at the bottom center, where there’s a small speaker icon. This goes on the top side of the board like the other components, and is soldered underneath.
• A 4-pin header goes to the ANALOG pins, also inserted from the top and soldered underneath.
• A 40-pin GPIO stacking header is installed the opposite way — inserted from the bottom and soldered on the top (component) side.

As always, be mindful of solder bridges, cold joints, etc.