I saw another related thread but it did not solve my issue.
I have a Ring doorbell generation 2. I have set it up to operate off battery and charge it every so often. Upon putting it on the charger from 13% battery, the entire blue light rapidly flashes. I re-seated the cable, tried various mini-usb cables including the included original orange cable, and various charging bases. All gave the same result. I left the device on the charger with the rapidly flashing blue light for approximately 6 hours. Upon removing it from the charger, i pressed the ring button and also allowed it to capture motion. The device still reports battery life at 13%