2nd gen doorbell not working correctly after charging

I plugged my 2nd gen video doorbell to charge earlier today and thought it had done. But the doorbell isn't responding when pressing the button, and it acting unusual. I put it onto disarmed mode while it was in the house then set it back to Home mode when done which has motion detection and live view enabled. I do this each time I charge it. Motion detection isn't working, apart from a couple of times randomly while I've been moving it about. I've tried changing WiFi connection and it has entered set up mode and says it's connected to the WiFi. It's very slow to connect to Live View, but doesn't always. In the Device Health tab, when plugged in it has been saying it's hardwired, usually it says it's charging. Currently it says it's running on battery but next to Battery Level says Add Battery. It's currently plugged in but not lit up in anyway. It keeps randomly without me doing anything, 1 top segment the blue light flashes 6-10 times then off for seconds, then flashing again. Some of the flashes are more like flickers as though it's trying to charge but power going. It's actually started doing this as I type after about 20 mins. I don't know if it's not charged correctly, although I have tried different wires and plugs, done some kind of update that's actually buggy or it's just broken. I've tried everything possible in the app and looked at all the Help section. ETA I have also tried to Reboot Device - a few times it's said it can't be done and to try again, other times the app says it's doing it but nothing is lighting up on the doorbell so presuming it's not doing anything.