Electrical issue after replacing radiator

Car listed above is a Series 2 Mazda RX-8. I recently replaced the radiator, which isn't difficult but requires much disassembly of the front end. I got it put back together and running. As I was purging air from the system, I noticed the radiator fans weren't turning on. I was monitoring the coolant temperature via a Bluetooth OBDII scanner and it was hot enough that they should have switched on. I shut the car down and decided to pull the three fan relays from the main fuse block and bench test them. They all functioned properly. I reinstalled them in the fuse block and turned the ignition to ACC. I didn't hear the normal sounds of the fuel pump and air pump starting up. Instead, I heard a relay clicking continuously. This was different from when there is something like a bad battery. This was a constant click. I shut off the ignition and disconnected the battery (which is almost new and never had a problem with it). I waited about 5 minutes and reconnected the battery, and switched the ignition to ACC again. Same result - constant clicking of a relay. I looked around under the hood to see if I could identify the source of the sound. I then heard a loud "click" and everything went dead; nothing, even interior lights, was working. I disconnected the battery again and looked for blown fuses. I found the EGI Comp2 fuse had blown. I have a Mazda service manual for he car and started following the troubleshooting, starting with the radiator fan relays, doing what I could without connecting he battery. For each of the three fan relays in the main fuse block, I discovered there was continuity between one of the relay terminals and the body ground for all three relays, indicating a ground short (most likely melted wires somewhere). The service manual says to repair or replace the wiring harness for corrective action. I do my own work, but I'm not sure where to start.