July 2019, had this same problem… Because it was late, I decided to call support the next morning, so that I wouldn’t be cranky.
Next morning, I awoke to find that the problem had resolved itself overnight. The camera has linked back up to the system, works just as before, and battery status now shows “OK” instead of “REPLACE”.
Not sure how/why it didn’t work while I was awake and watching. Maybe it’s that “a watched pot never boils” and I simply wasn’t patient enough.