The Polar H10 has a warranty, I can’t remember if its 1 year or 2, but I had mine warrantied in Jan 2024. Total turn around time was about a week, it was really fast.
For the Polars, you can also try a hard reset if its not working right–take the pod off, pull the battery and then hold both of the snaps for 30 seconds. Reinsert the battery and you should be good to go.