Welcome to the forum. It sounds like you are actually having a wiring problem. Do you have both a wiring diagram for the Challenger itself and the replacement wiring for the coil itself? You should have a ballast resistor mounted near the distributor, which is needed for the electronic ignition itself, without it the hall effect will burn out. The ballast resistor is white, rectangular, and you may have the four plug, two on each side, which reduces the voltage to the hall effect distributor. If you have power from the coil. From there, check the wiring with the wiring diagram first, then the rewire for the MSD setup. You can find the wiring diagram online, actually an easy one to find. Start with that.