Full Blue Ring Flashing

Hi all! I bought my Ring doorbell a little over a year ago. About 7 months ago I discontinue Wi-Fi service and brought my Ring doorbell inside. I forgot to keep it charged and now I am trying to set it up again and it won’t connect. I plug it in, and the blue circle light will flash for a couple of minutes and then stop. The orange button on the back does nothing when I try to connect it, and the circle never spins white, signifying it’s ready to pair. I’ve had it plugged in to a power source for several days and it still acts like it isn’t charged. Is there any way to replace the battery or do I have to buy new product?