Why is iPad constantly rebooting post battery replacement? See video

Problem: iPad Mini 2 just turns off seconds after turning on and then continues to reboot. At each alternate reboot the screen flashes red before shutting off and turning on again. Please see the short video. It shows me turning the iPad Mini 2 on and shows the iPad rebooting several times.

I am able to turn off the iPad Mini 2 by holding down the power button.

Context: I just replaced the battery of this Wi-Fi only iPad Mini 2.

Possible Useful Info: This iPad Mini 2 was repaired previously. When I opened it up the LCD Shield was bent and screws meant to hold down the LCD Shield actually went through the the metal LCD Shield.

When I received the iPad the battery was completely swollen and had lifted the front screen aka digitizer and did not turn on.

The owner of this iPad Mini 2 was not 100% sure it was a battery issue although seemed like the likely culprit.

My thanks to the iFixit community for your help.

Update October 26, 2020:

1. I’ve added photos of the motherboard. Both as it was when I installed the battery and then after taking out the motherboard itself.
2. Additionally owner did say that the reboot cycle with the red screen did occur before the iPad died from a bad battery. It had a charge battery signal with the constant reboot, so they thought it was just a battery issue. Obviously it was not.