Ipad air 2 weird charging issue

My mothers ipad air 2 stopped charging. Being 10 years old I bought the battery kit from ifixit and replaced it. Then it would charge but not if the battery got below 24%. It has to be forced into restore mode by holding home and power buttons. I found out she had been using off brand charge cable so that suggested bad tristar. So I bought a few of those and replaced it. The problems persist. The battery drops like a rock (10% every 15 minutes or so). Will not charge below 24% battery without restore mode. Only seems to charge after that if the tablet is off.

Has anyone had these issues? Could it be a faulty battery or PMIC? Im starting to worry its gonna burn her house down.