iPhone 6s Plus not charging after battery replacement

I replaced my iPhone 6s Plus battery using the iFixit kit. Once I got the phone resealed, I threw it on the original charger (adaptor and cord, known working) and it started charging right away after performing a hard reset. It started at around 20%, it was I walked away to do some other things and an hour or 2 later, I noticed it was at 46% but it was not charging. I attempted to connect it to my computer and it did not show up either in iTunes or as a device. Here are the things I tried to no effect:

• Hard Reset the phone
• Different cables, both in the wall charger and on the computer
• Turning the phone off and charging (plugging the phone in after it was turned off would cause the phone to turn on, but did not change charging behavior)

What I did notice is that in the process of turning the phone off and on, the area around the power button (on the side) was getting warm. From what I’ve read, these symptoms (no charge, no connection via USB to computer) might indicate that it is one of the power ICs (U2 IC) or that it could be a bad battery. I will try putting the old battery back in, but I may not be able to do that for the next couple of days.

Wondering if there is anything else I could try that I haven’t already outside of putting the old battery back?