Keep Your Nest Thermostat Running Without Google: A How-to Guide

I ran a Nest that stopped talking to Google. I flashed replacement firmware and got local control back. This guide shows the exact steps I used. It covers backups, flashing, verification, privacy options and Home Assistant Integration. Follow it carefully. Read the project docs and mirror the commands on your machine.

Getting Started with Nest Thermostat Firmware

Understanding the Need for Replacement Firmware

Google disabled cloud access for older Nest models. If your Nest no longer reaches Google servers, the device will lose remote features and may brick. The clear option is replacement Nest Thermostat Firmware that redirects the device to a different server. The NoLongerEvil project is one such solution that aims to restore local control for Gen 1 and Gen 2 Nest devices. See the project homepage and GitHub for code and releases: the project repo and dashboard are where to begin.
NoLongerEvil GitHub | NoLongerEvil dashboard

Overview of NoLongerEvil Firmware

NoLongerEvil replaces the network layer so the thermostat thinks it is still talking to Nest. The project provides build and installer scripts and a hosted dashboard. The README lists supported models and current limitations. Some binaries in the repo are closed, so review the issue tracker if you want full transparency. Expect the firmware to provide temperature control, mode switching and local status pages. It does not reintroduce Google cloud features.

Preparing Your Nest Thermostat for Flashing

Make these checks before touching the device.

• Confirm model: Gen 1 or Gen 2. These are the models the project targets.
• Power: turn off mains to the thermostat when you open the backplate. Use a multimeter if unsure.
• Hardware: you need basic tools, a USB-to-serial adapter (FTDI or similar), and jumper cables. The README shows the pinout for the Nest PCB. Take photos of your wiring before you disconnect anything.
• Host: use a Linux laptop or a small Linux VM. The build scripts assume a Unix shell and common tools such as git, curl, and make.

Backing Up Your Current Configuration

Do this first. You may need to return to the stock firmware.

• Photograph the current screen and menu settings.
• Dump the flash if you can. The build scripts include a read command for the flash chip. Save the binary somewhere safe.
• Keep the original serial logs. They help when troubleshooting.
  If you cannot dump the flash, at least keep copies of any configuration screenshots and the original device label.

Connecting to Home Assistant

If you run Home Assistant, plan the integration before flashing. NoLongerEvil aims to offer a server API that Home Assistant can use. At present, integration will usually be via a REST or MQTT bridge. My approach was this: install the firmware, point it at a local server on the homelan, then add a simple MQTT sensor in Home Assistant to reflect temperature and HVAC state. Expect to write a small template or use the HTTP sensor if a ready-made integration is not yet available.

Flashing the Firmware on Your Nest Thermostat

Step-by-Step Flashing Process

Follow these steps. I suggest reading the project README twice before you start.

1. Clone the repo and fetch releases. Example:
   • git clone https://github.com/codykociemba/NoLongerEvil-Thermostat.git
   • cd NoLongerEvil-Thermostat
2. Install build dependencies on your Linux host. Commands vary by distro. The README lists the packages I used on Ubuntu: build-essential, python3, git, and avr tools.
3. Put the thermostat into serial programming mode. That means opening the backplate and wiring the FTDI adapter to the correct pins. Label the wires.
4. Verify the serial connection. Use screen or minicom. Typical baud is 115200. If you get gibberish, swap RX/TX.
5. Create a backup of the existing flash with the provided read script. Save that file outside the project folder.
6. Build the image with the provided script or download a release binary. Be mindful that some parts of the installer are precompiled.
7. Flash the image using the installer script. Run it from a shell and watch the logs. The script will write the firmware and set the server URL.
8. Reassemble the thermostat and apply mains power.

I used these exact steps and a cheap FTDI adapter. The whole process took me under an hour, excluding backups.

Verifying Successful Installation

Verification matters. After flashing do these checks:

• Boot trace: connect serial and check for a boot banner that references NoLongerEvil.
• Dashboard: point the thermostat to the dashboard URL you set during install. The device should register.
• Local control: change temperature on the device and confirm the change in the dashboard.
• Home Assistant: confirm Home Assistant sees the state if you set up MQTT or HTTP integration.

If the device fails to boot, restore your flash backup.

Troubleshooting Common Issues

Here are specific fixes I used.

• No serial output: check ground connection and swap TX/RX. Use a fresh USB cable.
• Installer fails with permission errors: run the script as your normal user and prefix only the command that needs root with sudo. Do not run the whole build as root.
• Device loops at boot: restore the original flash and re-run the read step to confirm the backup is intact.
• Dashboard shows wrong timezone: change the timezone on the server config and restart the device.

Log everything. Logs are the quickest path to a solution.

Adjusting Privacy Settings

This is a key reason for replacement firmware. NoLongerEvil gives local control and avoids Google endpoints. After flashing set privacy in two places.

• Thermostat: disable any network features you do not need. Turn off remote logging if offered.
• Server: run the NoLongerEvil server on your LAN if you want full control. If you run a public-facing instance, secure it with HTTPS and basic auth.

I run the server on a local VM behind a firewall. That puts the device on an internal IP and keeps telemetry local.

Integrating with Smart Home Automation

For Smart Home Automation I used Home Assistant with a small MQTT bridge. Steps I recommend:

1. Enable MQTT on the NoLongerEvil server or use a local adapter script.
2. Create sensors in Home Assistant for temperature, humidity and hvac_mode. Use explicit topics and set payload types.
3. Use automations sparingly. For example, trigger heating only when the house is occupied and the external temp is below a threshold.

Home Assistant Integration will improve as the community adds an official integration. For now, an MQTT or HTTP bridge gives reliable control.

Final takeaways: back up before you touch the device, follow the repo instructions, and verify with serial logs. Replacement Nest Thermostat Firmware like NoLongerEvil can restore local control and better privacy. The project repo and dashboard are the single source of truth for releases and detailed commands.