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Original Poster: William Cheng 4870
Sorry to hear about your login issues! I can totally get the frustration. I'm happy to look into this for you.
Since your Hub and Nest Thermostat can work together with Google Assistant, you will need to migrate your Nest account to your Google Home account. This way, your devices should automatically sync. Here's how to migrate your account. If you used the same email for your Nest account and Google account, merging should be fairly simple.
Let us know how it goes! I hope this resolves your issue.
-From Garrett DS, Community Specialist.