Top Speaker / Headset Not Working

[Jake52]

I've been running Windows 10 preview builds on my HTC One M8 for AT&T and everything has been working great but after the I upgraded to the last one (I forget the build number) the top speaker stopped working. So when I play music or anything only the bottom speaker works but more importantly, when someone calls me I can't hear them because the top speaker is also the headset during calls. I went back to 8.1 using the recovery tool but the speaker is still not working back in 8.1 so I'm thinking it's a hardware issue.

Has anyone had this problem and were able to fix it?