The order switcher board certainly looks like everything is where it should be to me. That being said, you said it worked with the two pedals connected together - which I assume means that you had the in jack running to the first 3PDT, a wire from the out of the first 3PDT to the in of the second, and then the output from the second 3PDT running to the output jack. So you actually had to disconnect a lot of wires to insert the order switcher in there, since most of the wires I named are now going to and from the order switcher rather than the two 3PDTs.
1. I know you said you’ve checked all of the hook ups – but are you sure that nothing is shorting out somewhere? I know that just the act of taking a working pedal back out of the box to make changes can introduce the risk of an unanticipated short almost anywhere when you put it back in the box. Or, if you were doing your testing outside of the box, perhaps a short was introduced when you put the whole thing in the enclosure - i.e., something touching the enclosure or something else that it is not supposed to. Just something to check.
2. Other than that, if everything worked without the order switcher and you’re sure that all of the hook ups are correct and there is no short anywhere, that would seem to leave the actual mechanical switch as the only culprit.
Good luck!
Best,
Mike
