it won't install with the app, i get to the wifi step and it just spins forever then says setup failed

Diagnosis

The "spinning wheel" failure during the Wi-Fi provisioning phase of the Amazon Smart Thermostat installation is typically a handshake failure between the Alexa app and the device's temporary Access Point (AP). This happens because the thermostat creates a local, unencrypted Wi-Fi network to receive your home network credentials. If your smartphone's operating system detects that this temporary network has "no internet access," it will automatically jump back to your cellular data or your primary home Wi-Fi, severing the connection before the credentials can be transmitted. Furthermore, this failure is often triggered by "Smart Connect" or "Band Steering" on modern routers. Because the thermostat exclusively uses a 2.4 GHz radio, a router that merges 2.4 GHz and 5 GHz into a single SSID often confuses the device during the initial handshake. If your phone is locked onto 5 GHz while trying to push settings to a 2.4 GHz device, the provisioning packet is dropped, resulting in the generic "setup failed" message after several minutes of attempting to connect.

How to Fix It

To resolve the provisioning loop, follow this precise sequence to ensure the handshake is not interrupted:

1. Power cycle the thermostat by removing it from the wall plate for 30 seconds and snapping it back in to clear any cached setup attempts.
2. On your smartphone, go to Settings > Privacy > Location Services and set it to "Always" or "While Using the App" specifically for the Alexa app. Disable any active VPNs (like NordVPN or Google One VPN) and turn off "Private Address" or "MAC Randomization" in your phone's Wi-Fi settings for your home network.
3. If your router uses a single name for both bands, log into your router admin panel and temporarily disable "Band Steering" or create a dedicated 2.4 GHz guest network with a simple password (avoid special characters like emojis or non-standard symbols).
4. Open the Alexa app and start the "Add Device" process. When the app prompts you to connect to the thermostat, open your phone's Wi-Fi settings manually and look for a network starting with "AMZN-". Connect to this network explicitly.
5. Once connected to "AMZN-", immediately switch back to the Alexa app. If your phone warns you that the network has no internet, select "Stay Connected."
6. Select your home 2.4 GHz Wi-Fi network from the list and enter your password. Wait for the thermostat to blink green, indicating it has successfully migrated from the AP mode to your home network.

If That Didn't Work

• Perform a hard factory reset on the thermostat. Press and hold the reset button (or the specific button combination for your hardware version) until the screen flashes. This wipes any partial network profiles that may be causing a conflict during the second attempt.
• Try the "Bridge Method." Use a second smartphone or a tablet as a temporary hotspot. Set the hotspot to 2.4 GHz, connect the thermostat to that hotspot, and then attempt to migrate it to your home Wi-Fi. This confirms if the issue is the thermostat's hardware or your specific router's firewall settings.
• Check your router's security protocol. If your router is set to WPA3, the Amazon Smart Thermostat may struggle to connect. Switch your security setting to WPA2-AES (CCMP) and try the setup again.
• Update the Alexa app to the latest version and clear the app cache in your phone's system settings. An outdated app version often contains bugs in the provisioning handshake logic for newer hardware revisions.

Heads Up

• Ensure your C-wire is securely connected; unstable power delivery to the thermostat can cause the Wi-Fi chip to brown out during the high-power draw of the provisioning phase.
• Avoid using special characters like &, %, or # in your Wi-Fi SSID or password, as these can cause parsing errors in the thermostat's firmware.
• Keep your phone within 3 feet of the thermostat during the entire setup process to prevent signal attenuation during the AP handshake.
• If you use a mesh network (like Eero or Google Nest Wi-Fi), temporarily disable the 5 GHz band in the app settings until the thermostat is successfully onboarded.