The above-referenced AirPort Express is known for faulty power supplies. Mine gave up the ghost a couple years ago and the stay-at-home orders gave me some extra time to fix it up. I used a mess of instructions here and here.

Ultimately this repair failed again, but my soldering skills and hot air machine skills have improved since then, I may give it another go at the board level… And a good friend has a Time Capsule that also has a failed internal power supply. If we open his again, we should consider a repair with these instructions. I’ll update this post later if we get it to work.