New battery gets hot and discharges too fast

Battery replacement went okay, even replaced the screen gasket. Battery charges to 100% but discharges quickly. Front and rear are warm when the phone is just sitting on the table. Battery discharges in about 4 hours, even if not using phone at all. It’s not even logged into an iCloud account (it’s wiped and just sitting at the default home screen or the screen is off). There are no apps installed, just a default reset. Must be a short somewhere but any clues how to find it?