MacBook labors during startup after battery replacement

I replaced the battery on my macbook today and noticed issues immediately. The OS loading process was extremely slow and there was a weird error message that said hit any key or wait a few seconds to continue booting.

Not long after that message, the fan was running full speed and eventually got to my login screen where I could enter my password. This was also extremely sluggish and it seems like the system never fully booted up.

I shut it down and tried to reset the SMC a few times but nothing worked. At any rate, I reinstalled my old battery and am using the device to post this. Did I mess something up during the install? Is the new battery faulty? I'm very confused at this point.