Whoever made this needs to add a license right now with at least some kind of indemnity/no-warranty clause. If something goes wrong, the user can sue you, and likely win. Your nolongerevil.com website also needs a EULA w/indemnification before allowing users to register.
The user is going to win after going out of their way to install an aftermarket binary blob on their deprecated thermostat? Seems like a stretch no?