Ok, I fixed it. The aux input had popped cleanly off of the board, but the contact pads were left behind. I had to take off the rubber casing (with my hands/fingernails), and unscrew the bottom bay. It is a little tough to get the main PCB out of there, but not too hard. Disconnect the battery (I used a toothpick to push it out from the top of the connector, since it was tightly pushed in), and place the jack back on the board, with the pins aligned. I carefully soldered it back on with a fine, curved tip (Hakko T18-BR02). I replaced everything after verifying it worked.