iOS 11 bricked my device

My battery had gotten old and since my warranty was already gone, I replaced it with a high quality replacement. It wasn’t a crappy one from China or something. And this worked for almost 6 months. Then I updated to iOS 11. After two days I was low on battery when my iPhone restarted twice then died. I plugged it in over night and tried to turn it on using every trick in the book. I took it to the Genius Bar and they did the same things I did to no avail. I had smartly saved my older crappy battery and when I turned home I opened up my phone and put in the old battery and, presto it worked perfectly. I know apple doesn’t support 3rd party screens and batteries but I’m pretty sure these two batteries are completely identical in all but casing. I’m writing this question because I want to know what went wrong and how replacing the battery fixed it.