Speaker option greyed out, but mic and earpiece audio still work fine

I’ve been getting mixed information regarding the issue where my iPhone 6 Plus has no loudspeaker audio and the speaker option is greyed out (also, I cannot adjust the volume unless I have it connected to a bluetooth audio source or have my headphones plugged in). However, my mic appears to work as I’ve tested it via phone calls and the Skype test call, though whenever I try to use the Voice Memo program, it completely crashes it, and I still get audio through the earpiece and through external audio sources.

From what I’ve gathered in previous posts and on other forums is that it’s probably an audio IC issue that requires microsoldering. However, I’m a little confused since everything else audio related on my phone appears to be working fine and it’s not completely broken. Is a disabled loudspeaker the main symptom of a bad audio IC? Or is there a possibility that I just have a faulty loudspeaker, as this would be the difference between spending $100 for a new chip or $20 for a new loudspeaker.

I’ve already had my iPhone 6+ repaired for touch disease about a year ago and I recently had to replace a faulty vibration motor. When doing the repair, I saw that a lot of screws had become loose or dislodged. I’m not sure if this was because the repair shop I used just didn’t tighten their screws or if the vibration motor just shook everything loose, and was wondering if that could also have caused a problem.