Ring won’t charge

Our ring will not hold a charge. It was at 30% for a day and then it went to 15% and won’t get higher. We have charged it for three days and it won’t go higher than 15%. What can we do? How can we fix this? Is it a bad battery in the ring? We can’t hard wire it to a doorbell system because we don’t have that at our house. Any help is appreciated.