I thought this might be useful for anybody having the specific problem I had. I received a used Ring Video Doorbell 2 from a friend that was supposedly in good working condition. I wired it directly to an Ohmkat transformer. After installation, I noticed under device health that the battery was not charging (it was operating in battery mode). I checked voltage at the screw terminals on the back of the doorbell and read 20VAC. I decided to take the unit apart (removed the 10 small Phillips screws on the back of the doorbell) and separated the case. I found that there are 2 small spring loaded pins inside the unit that make contact with 2 screw terminal posts on the back casing. However, I noticed only one of the pins was extended. The other pin collapsed on itself and wouldn’t allow connection to the back post. I tried pulling the pin out but it would just collapse back inside itself. My high-tech temporary solution is shoving a rock behind the doorbell to flex the center inward and engage the pins. Permanent solution will be soldering wires directly to those pins.