One possible cause is that the "chime puck" is not correctly wired (or is defective; a few defective "chime pucks" have been reported in this forum). See the diagrams on this Help page:
@Bceballos thanks for reaching out. I know where you're coming from when you say your Nest doorbell won't stop ringing. To confirm, have you tried double checking the chime puck? Do you have the battery or wired type of Nest doorbell? Try to perform a simple restart to your Nest doorbell.
Keep us posted.
I appreciate the help, MplsCustomer.
There have been several posts in this forum with the opposite problem with the "chime puck" for the new 2nd Gen Google Nest Doorbell, with many of them reporting their doorbell chime not working, and several customers have gotten replacements: