sorry, I thought I was clear in suggesting it as a law - although realistically in a lot of EU countries you could make the case and get it returned.
For example I'm in Denmark and we have a consumer ombudsmand were you can make complaints about violations of your rights as a consumer https://www.consumerombudsman.dk/about-us/ (it talks about marketing but I the Nest was marketed to have functionality it no longer has), in fact there may already be sort of an Ombudsmand ruling that pertains here https://www.consumerombudsman.dk/media/46530/2016-memorandum... which says you can return something after your normal right of return but you are liable for diminished value - so you would not get the full refund in this case but something.
Of course I think that an actual complaint on this subject would result in a memorandum that you can get your full refund.
Update - I had an opportunity to ask someone who definitely knows exactly what the rules are in Denmark and they said that if Google refused to refund you would have to take them to court but they are also certain that any eventual legal process would find Google liable for refunding as long as the Nest was ever marketed for its now no longer functioning capabilities.
The problem is you’ve voted with your dollar already. You’ve looked at the market and selected the one that meets your needs. Then the maker changes what you’ve purchased.
Yeah, it would end up hurting the upstarts, but the lack of this law hurts customers and hurts business on the long term because consumer trust evaporates.
For example I'm in Denmark and we have a consumer ombudsmand were you can make complaints about violations of your rights as a consumer https://www.consumerombudsman.dk/about-us/ (it talks about marketing but I the Nest was marketed to have functionality it no longer has), in fact there may already be sort of an Ombudsmand ruling that pertains here https://www.consumerombudsman.dk/media/46530/2016-memorandum... which says you can return something after your normal right of return but you are liable for diminished value - so you would not get the full refund in this case but something.
Of course I think that an actual complaint on this subject would result in a memorandum that you can get your full refund.