I got a replacement battery from Amazon (there are many of course), but it was a waste of time. The battery works, but the faceplate is broken into multiple pieces and torn up around the edges, no matter how careful I was at trying to pry it up. I doubt the doorbell will survive the elements for too long. I put an Elago silicone cover on it (covers most but not all of the broken areas).

Nest/Google should be required to refund or replace these; a $250 doorbell that can't last 4 years (and isn't designed to have the short-lived part easily replaced) is defective by design.

And iFixit saying "do not be afraid to pull hard" on a thin piece of plastic that's heavily glued is part of the scam.