The next day after publishing my Installing Nest Hello Doorbell To HDB BTO Doorbell post, my Nest Hello Doorbell decided to give up on me.
I received the Nest Hello Doorbell (Wired) on 7th September 2021, and on 9th September 2021, the first problem occurred. There is no ring light around the Nest Hello. I restart the Nest Hello by switching on and off the transformer plug, and it works great after that.