After resetting, I was able to select the access point and assign a name to it. It then asked for a Wi-Fi network, and the list included 5GHz networks even though the app says the current device is 2.4GHz only.
I selected a network and the red light on the device changed to pulsing blue after about 15 seconds, but the app showed a progress bar for a few more seconds and said it failed to connect.
When I dismissed the error message on the connection screen the access point appeared on the screen anyway and I was able to connect it to my Sesame. It works fine now.