iPhone 7 Dead Battery

I recently upgraded to the iPhone 12 Mini from an iPhone 7, I decided to keep the 7 for other purposes. The phone is about 2 years old, I always used the original charger brick + cable on every single charge. After getting my iPhone 12 Mini, I charged the iPhone 7 about 2 times with a 20W charger, I didn't use the phone and left it on the table, so it ran flat, when I plugged in the phone on the charger again. It was on an apple logo loop, it also doesn't look the phone is receiving any power from the charger besides just keeping the phone on. I was able to boot into recovery mode. Tried restoring on iTunes, it extracts the software and "prepares" the iPhone. The phone then shows the apple logo with the loading circle at the bottom and shuts down and goes through the same cycle without ever restoring. Is this a battery issue or something else? The battery's maximum capacity was over 80% before it just died.