A fancy texting device, huh? Yeah that ‘s no fun. Sounds like when you reconnected the battery and the speaker part, could be that the seal is not entirely secure. You stated that it took of time to put it back together, which sometimes in the process, the right amount of pressure and/or screws are not placed correctly.
Now, in the case that the part you got in indeed faulty, obviously you’d have to swap it out. Either way, you’d have to reopen the phone and see what the problem is.
What I’d recommend, is to get another speaker part, just be careful with the TouchID, since you can disconnected by mistake and create another problem. Seal it back up with the help of an iSlack if you have one. If not, just gently apply pressure along the edge to make sure it’s enclosed correctly.
Any questions, let me know.
Alex H.