Help - hardwired doorbell not charging

Hi, I've wired up my Ring Video doorbell to my existing 19VAC doorbell supply. I've removed the existing doorbell. I've inserted a 25Ohm 50W resistor as specified in the instructions, in series with the doorbell. The resistor is HOT to the touch, and there is about 8VAC being dropped across it, and about 650mA current flowing to the Ring. The button on the doorbell is glowing WHITE continuously, which I think indicates that the unit is receiving power. (Right ?) The ring doorbell itself is also 'warm' at the top of the housing around the camera area. The doorbell does work normally. However, on the application on my phone, it reports that the doorbell is powered by 'battery' and the battery is indeed discharging, albeit slower than usual I think. I've tried removing and re-installing the battery = no change. Any ideas what could be wrong or further troubleshooting ? Could my doorbell be defective ? We've owned it for about 2 years and always used it on battery. Thanks Mike