Replaced battery. Worked fine but no sound. Now won’t start.

I just replaced my 2015 Retina MacBook 12” battery. I followed all the instructions and everything seemed to be fine. However, I noticed that there wasn’t any sound coming from the system. It listed both the internal speakers and headphone jack in the system prefs, but no sound came out of either. However, the system did pick up sound with the internal mic and Bluetooth headphones worked just fine.

I thought maybe I had a bad cable connection, so I drained the battery and opened it up to check. I accidentally disconnected the trackpad before pressing the battery drain button on the logic board (however, I did that right away once I realized). I made all my other checks, closed it up, and plugged it into a 5W charger to prep the battery before booting up. However, now it won’t boot at all.

Did I fry my logic board?! Is there any fix for this? Assuming I can get it started up again, any ideas on how to fix the sound?

Many thanks!