MBP13 Late 2013 no sound and no input/output device listed

[JChristian]

A family member has a MBP13 Late 2013 that worked flawlessly until recently when sound stopped working. The MBP13 has no fall damage and no water damage. Events are as follows:

1. MBP13 was running macOS Mojave and updated to Catalina some weeks/months ago and didn't notice any issues, but some days/weeks after the update, while watching YouTube, the MBP suffered a kernel panic related to coreaudiod. He restarted the system and got no audio after that. He got the "no sound" icon when trying to change volume.
2. I did a search and found the following command to restart coreaudiod: sudo kill ps -ax | grep 'coreaudiod' | grep 'sbin' | awk '{print $1}'. It worked, but for a short period, after a day or two the audio stopped working again and he got the same “no sound” icon. I tried the command again, but now it didn't work, not only that, inside system preferences > sound > output/input there was no devices listed (internal speaker and mic should be there).
3. Did NVRAM reset multiple times, didn't work
4. Did SMC reset multiple times, didn't work
5. Installed clean macOS Mojave, didn't work
6. Updated to macOS Catalina, didn't work
7. Tried plugging in P2 headphones, didn't work, system preferences won't even list them in sound input/output
8. Bluetooth headphones work, they are listed in sound input/output
9. Opened the MBP13 and disconnected and connected the left and right speaker, didn't work

I'm afraid this is a hardware failure, I don't know if it's a logic board issue or speakers issue. If it were only the speakers, the internal mic should still work, right? But, that's not the case as the mic doesn't work either. What do you guys think?