And sure enough, that was the problem. The the corrosion on the fuse holder wasn't letting it make contact with the end of the fuse. So even though I was showing 12 volts on both sides of the fuse, the power wasn't making it to the wires connected to the back of the holder. Cleaned it up so it got good contact, and everything is working again. Crazy that it could happen like that. Oh well, at least maybe my posts to myself will help someone else haha.