Original Ring Doorbell Will Not Hold Charge While Hardwired

I have an original Ring Doorbell a few years old. Recently I've noticed that even though it is hardwired, and shows charge coming through on the app, the next day it's disconnected from my network. When I remove it, it is completely dead and I have to charge up on a charging cable before it will even respond. I have done this process 3 times, and each time I reinstall it seems like it's resolved (100% battery and shows connected to hardwired power) then the next day it's dead again. The doorbell is definitely getting power, checked with a monitor, and when you press the doorbell it does ring the house chime.It seems the battery is simply dead at this point and won't hold a charge. Any advice, or will I need to replace it?Thanks!