Took my bike to the LBS today. The shop did pretty much the same things that Sierratim said that he'd do. They took apart a bunch of stuff, examined it, cleaned multiple terminals and tested things. They couldn't find anything except one small thing. They said that recently Specialized upgraded the latch that holds the battery in place, since so many Vado have loose batteries. They said that my bike even though it was a 2020, had the old style latch, so they changed the battery latch to the new upgraded one. The shop tech was pretty certain that it was a deceptively loose battery that caused the error message and that it was now fixed. He told me to ride the bike like normal and if it happens again, they'd replace all of the innards of the bike (whatever that means) under warranty.
It rained here this afternoon, so I could only go for a 10 mile ride in between downpours, but all was well for that distance.
Anyway, that's epilogue to the story. At least for now. Thanks again to all!