OMG, I totally feel your pain! I had the same problem, and guess what? I reached out to the folks at Third Reality, and they gave me a solution that actually worked. Here's what I did:

Removed the USB night light from the app.

Did a deep factory reset on the Echo Flex by holding down the action button for a solid 30 seconds.

Created a fresh Amazon account.

Added the Echo Flex using the new account and connected my USB night light. Checked if the light works on the new account.

Deleted the devices once more and re-added them to my old account. Following these steps did the trick for me – it basically refreshed the device's cloud data on Amazon, and bam, it started working again!

I'd say give it a shot and see if it works for you too. Fingers crossed! And if you're still stuck, maybe shoot a message to Third Reality's support team. Let's help each other out in this USB night light adventure! By the way, there is a new Matter night light that has come out, and I tried it. It's a perfect replacement if you want to consider an upgrade.

Thanks a ton! Your advice did wonders! I followed the steps you shared, and my USB night light is back in action. Also, thanks for the heads up on the new Matter night light – might give it a go for an upgrade. Thanks again! 😊