Ok so my daughters iPad mini 4 is having an issue. We will leave it in the car for less than an hour with outside temps around 36-39 degrees F and it will be shut off showing the dead battery symbol. So go to plug it in knowing it’s not dead and it comes back on and will show anywhere from 9%to 65% right at start up. So my question is what’s going on ? Is the battery going bad? It never did this before a couple weeks ago. How do I test it to see if it’s the battery?