Ring Doorbell 2 won't power on

Been using Video doorbell 2 for about 3.5 years now just on battery. Haven't hardwired it at all. Worked perfectly fine up to a few days ago when i removed the battery as it had been drained out. Charged it up as usual and inserted it back into the doorbell. I noticed it hadn't turned on i.e the light didn't start blinking is it should. I checked the app and it said the doorbell is offline as expected. I have been using a solar charger for it as well and it also wasn't showing connected. Could the battery be dead despite being able to charge to 100%. If so, how do i troubleshoot this issue? Any help is appreciated.