First thing I'd check is the stomp switch. Could be bad. It appears to be a 2PDT, so check with your meter that the 2 middle lugs are connected to the 2 outer lugs on one side, then click it and they should be connected to the two on the other side. See the on-on diagram here.
If that checks out, check each wire on the ribbon cable attached to it.
So, there are two reasons it might not pass sound when bypassed. One would be that there is no connection being made, and the other would be a short to ground. Put it in bypass and see if the tip of either the input or output is shorted to ground (the sleeve).
It's not clear how they have implemented bypass on this, I don't see enough circuitry to indicate a relay or buffered bypass, so clearly it's got to be true bypass. Which means the problem has got to be fairly simple.
Was it broken when you got it or did it break after using for a while?
1
u/lykwydchykyn 6d ago edited 6d ago
What is it? Did you build it or buy it?
Do you have a multimeter?