Same issue here. Ring 2 been working fine for past few years. I noticed it went offline a month or two ago. Finally got around to looking into it today and found the battery completely dead. Measured the wires on the back and get 20V AC.
Charged the battery inside for an hour or so, put it back in and the doorbell powered up. I had to reconnect it to WiFi. It started getting a firmware update, so hoping whatever problem that happened with previous firmware is fixed in this version. However, the power status says its losing power.
I am told that anything under 0 degrees Celsius the battery will not charge. This is total insanity, and definitely a design flaw of major proportions. Many things charge at any temperature when hooked up to external power source. WHO THE HELL INVENTED THIS CRAP.
Been about 60 here most of the past few months so my particular issue is not temp.
IMO they screwed up something and are not fessing up, presumably due to all the other bad press
I wonder also if all this crap has happened since Ring sold to Amazon. I bought my unit long after the changeover and have only had it a few months. Perhaps Amazon is trying to recoup their purchase cost by scimping on value of the units and the circuitry. Just a guess.