pixel 3 constant battery drain

I recently replaced my 2 year old pixel 3 battery and charge port due to poor battery life and not being able to charge on the google issued usb-c charger (possible water damage).

While both of those issues are fixed now, I’m seeing a crazy amount of battery drain on the tune of 5-10% an hour. It is possible that this was occurring before the replacement, but I just didn’t notice due to the poor battery life.

Even after doing the battery calibration and turning on battery saver, airplane mode, safe mode, factory resetting, etc, I am still seeing constant battery drain per hour. The last test I did was to turn to turn the phone off overnight at 80%; when I woke up in the morning, it was dead at 2%!

This makes me think it might be a hardware issue, or something isn’t allowing the phone fully shutdown.

Does anyone have any ideas what it might be, or what else I can do to try and fix this? Thanks!