Hi Peter28,
Thank you so much for posting in this community. I’m sorry to hear you’ve forgotten the PIN of your Nest Learning Thermostat 4th gen. Don’t worry; it’s a pleasure to assist you.
If your thermostat is still connected to the Google Home app, follow the instructions:
- Open the Google Home app.
- Tap the name of your Nest Thermostat.
- Go to Settings, then Thermostat.
- Tap Lock, then confirm that you want to unlock your thermostat.
If your thermostat is not connected to the Google Home app, follow these steps:
- Use a personal computer (Windows, macOS, or ChromeOS).
- Get a USB-C data cable.
- Remove the thermostat display from its base.
- Insert the USB cable into the USB port on the back of the thermostat display, and then attach the thermostat display to a computer using the USB cable.
- Press and hold the thermostat display until it reboots and beeps into mass storage mode.
- Locate and open the folder or icon for the Nest device that should appear on the computer screen.
- You should find the technicalinfo.PLIST file. If it doesn’t show up, try using a different USB data cable, port, or computer, if available.
Let me know how it goes to provide you with further assistance.
Best regards,
Daniel
