2008 Ford Explorer steering wheel volume not working

[Sully22]

Hello, I’m new here so I hope I’m doing this right. Lol I have a 2008 Explorer that I just had a small amplifier installed in and now the volume and search button is not working on my steering wheel, all other buttons are functioning properly. the tech who installed the amp has no idea why that would be he never had to touch the harness that connects to the steering wheel. He even took a look and sees no issue. Any idea as to what happened? Thanks in advance.

 

[3C24]

My first thought is unhook the amp and see if the controls work again to narrow the issue.