New Nano, same code, Alexa fails

I have a Nano33 providing the interface to Alexa and thence controlling my lights. I changed the name of one thingProperty and propagated the name change through the main code. It compiles and loads normally. When I ask Alexa to turn on a named light circuit, she responds with the standard "done it" ping sound. But the light circuit doesn't respond. I plug the initial Nano33 back in and I get a good response, all the way to turning on the circuit.

Does the new Nano33 have some kind of ID that needs to propagate through the Alexa link? For example, does the THING_ID change with the new chip (it doesn't appear to, but that's just an example)? Does the new Nano33 create a new "thing"? When I disconnect power to the Nano33 and ask Alexa to turn on a circuit, I still get the "done it" ping from her. Why does she still think that the "thing" is out there if it's not connected?

I had a thought that maybe I needed to go into the Alexa app and find a new Nano "thing." Nope, not as far as I can tell. Alexa still sees all the devices (named lights) that are in the original code and there's no "thing" to find, or at least no "thing" that shows up as unidentified device.

Does this mean that if you have a Nano failure, if you replace it with another Nano and identical code, there is some "discovery" step required to ID the new Nano?