MacBook not recognizing a battery is installed

I discarded the old battery from the MacBook as it was swollen. Installed an iFixIt battery, as I've done with other MacBooks, but it will not power on. I've checked, double checked, and rechecked my steps, but still no dice. The MacBook will power on and everything works when plugged in, although the fan spins at max speed, indicating no battery is recognized. When the MacBook isn't plugged in and I attempt to power it on, nothing happens. Even when we thought "Oh, just let it charge" and plugged it in for a bit.

When the MacBook is plugged in, it doesn't recognize a battery in System Preferences or the menu bar.

My first guess is the new iFixIt battery is faulty, but I could be missing something. Battery data ribbon cable was installed successfully, but it could just be a bad battery.

I'm stumped. Any tips?