Your questions as usual lack of a better elaboration or at least less sloppiness: The attached picture is totally useless in the sense that it is impossible to read the silk legend on the top of the board. Another thing is that in the title says "bypass-no-output" but in the body of the post it is presumed you said "But-No-output" which are different scenarios. Also the link is dead, but you should already know.
Anyway, back to the question: What have you measured so far? Is there voltage at the input and not at the output? If the only device between both would be supposedly one of the Relays, have you measured it to know if it is switching and has electrical contact ?
Anyway, back to the question: What have you measured so far? Is there voltage at the input and not at the output? If the only device between both would be supposedly one of the Relays, have you measured it to know if it is switching and has electrical contact ?
No need to upload more pictures, the only thing you have to do is to measure backwards from the output to input, checking where exactly the contact is interrupted. The by-pass operating mode is as simple as it could be, usually only one relay is what detaches the output from the input.