Battery Replaced - MBP won't start, now with three beeps

Hi All,

As the title says - I purchased an iFixit battery replacement, as well as a new mag-safe port on my 2012 MBP Retina. The computer previously worked without issue.

During the replacement process my right speaker connector pulled off the from the logic board with very little force; besides that there were no issues and everything uninstalled and reinstalled without issue.

Now when I go to power on my laptop I get three slow beeps, a pause, and it repeats. There is no screen activity. I took to bottom cover off and the two fans are spinning slowly so I know it’s getting power. I’ve tried the power reset without success.

I’ve obviously either broken something or reinstalled something incorrectly; however, I don’t know where to begin to diagnose the issue.

Thanks for any help you can provide!