Good news and bad news. The good news is it's charging and riding fine again. The bad news is the check engine light is on and I can't figure out why or how to get it to turn off.
Getting it charging wasn't too bad. The charging circuit fuse is indicated by the red arrow. Pointing towards the base of the bike, there's a flathead screwdriver slot. Push in and unscrew ~1/4 turn to get the fuse holder out of the body. The fuse holder with fuse, and body, are sketched in an attached picture. I cleaned the contact on the holder, and scraped the mating contact inside the body clean with a small flathead. Then cleaned out the resultant black plastic shavings. After reassembly it worked fine. The fuse itself read *BUSS*ABC10A, which is a different manufacturer than I expected, but no big deal.
Now, the check engine light had come on a few days beforehand when I was downloading logs. I was assuming it would go away after I fixed the charging problem. But a couple weeks after cleaning the fuse contacts, charging to full and load balancing for 12 hours, and riding a few times, it's still there. I don't see much in the logs of any value. There are errors that existed long before the check engine light came on and so I assume aren't responsible, but nothing that seems to have cropped up at the same time as the check engine light. The manual says the check engine light will bring with it a decrease in torque, but I'm still able to get up to at least 75MPH. I suspect it'll go higher, though I haven't been able to test its old top speed of 85MPH, and it doesn't feel sluggish at lower speeds so maybe there's no actual torque reduction.
Logs to follow in the next post as I'm out of attachments