Thanks for reaching out to us here @AdrianPi . I am sorry to hear you are facing difficulties with your device and I would be happy to try and assist.
Should you wish, like @David_K suggested, you can reach out to our support line and my colleagues will be happy to try and assist. If you wish, I am also able to help out.
If you haven't already, check the breakers and switches at the location, to make sure nothing has tripped. Also check the boiler as it can sometimes have a separate switch on it. Confirm it has power, it should have a display or LED that turns on.
If it all looks good try and power cycle the Heat Link, if you're comfortable in doing so. Turn the power to the Heat Link off for a few minutes and then turn it back on. See if it has any reaction after, when you press the button on it.
Also let us check a few things:
1. When was the thermostat installed?
2. When did you first notice this behaviour?
3. Was it installed by a Nest Pro or by a heating/electrical engineer?
4. Did you notice any message on the thermostat display?
5. Did you notice any power cut in the area before this occurred?
6. Did you have any maintenance done on the heating or electrical system recently?
7. Do you have only one or multiple Google Nest thermostat devices at the location?
