So good news. I finally got around to reflowing the joints. First I tried resistors, no luck, then the rest of the joints, still nothing. I tried again today and reflowed most joints, really paying attention to any that didnt look like a picture of a good solder joint. Still nothing. Feeling pretty defeated and frustrated, I went to short the volume pot again to make sure I didnt damage that circuit while reflowing, and I got a very transient, louder buzz, and then the keys started working. It seems like the pots arent very precise, I probably got them too hot or still dont have good joints on them. Sometimes the keyboard seems to hold a note. Not sure if that is a setting I accidentally turned on or some other thing I messed up lol. Its really cool that its at least making sound and responding to keys and pot adjustments now!
Edit: I also used a toothbrush and some isopropyl alcohol to clean all the excess flux on the solder side of the board!