What stage are you at in construction? What you should have done (might be at this point) is once you have the PCBs equipped with diodes, test each switch-hole with a multimeter to be sure energy flows in the right direction. Actually I tested each diode right after soldering it in place but that does leave your iron heated for nearly twice as long over the course of the project.
Then, when you attach the Teensy and load it with firmware, use a pair of tweezers and a program like Aquakeys, to make sure all those switchholes are talking to the uC, and only then, when you've proven you have a fully functioning keyboard, do you start to attach keyswitches.