Anyway, after shutting the truck completely off again, locking it, letting it sit for a while (likely not much of a factor), unlocking it, and starting it back up again, the FM tuner came on immediately, and audio was back.
I shut it down again, brought the phone to the truck, started it again, and the truck’s display was totally black. No Dodge/Alpine logo, nothing. After a few seconds, I pressed the power button on the volume knob a few times, the display then came to life, got the Dodge/Alpine logos, and it worked as it had been before this last issue.
Not confident it’s fine, as I’ve had a black display in the past (for quite a bit longer), but at least it’s up and running for now.