Ring doorbell 3 say it on battery but its connected to power

I have the Ring 3 pro. I have had it for over a year with not problems charging until about two weeks ago. It has been hard connected to the doorbell wires since I have owned it and has always keep the battery charged. The weather is warm and I have a good wifi signal. I just took it apart to charge the battery and check that the wires were still connected and no corrosion.