My ipad has power and battery issues

the iPad I have has a few issues so I will sum up what the issues are that might contribute to my question.

I got the iPad last year refurbished, when it arrived the screen was partially separated from the LCD screen, I used tape to keep that part of the screen down.

a few months ago my iPad stopped charging, I changed chargers and wall outlets and even tried charging it at a different house.

I noticed that in the lock screen the battery percentage would be different than after the iPad unlocked (jumping from 75 to 15), also when it did charge I went into the battery settings and it showed that the iPad hadn’t charged and just suddenly jumped to a higher battery percentage

thinking this was an issue with the battery I replaced it.

after I replaced the battery not only did it not fix anything, my iPad would shut down every couple of minutes.

any idea what is wrong with the iPad? how I can fix it? I need to get it working asap thanks yall