I just fixed an issue where my power LED would not turn off. Not sure if it's related to your no sound issue, but for me the issue was that too much Solder flowed through the lugs of the footswitch and I had a solder bridge UNDERNEATH the 3PDT breakout board that I used.
However upon looking at the schematic above, it shows the LED wired DIRECTLY to the DC jack?? If this is true, there is no way to turn off the LED once DC Power is plugged in. Maybe I'm reading the schematic incorrectly?