Another "Won't Start" thread......

Newbie whose read about 100 "won't start" posts but haven't found one quite like my issue. Bought my neighbors 04 RX-8 with 78K miles. He was pretty meticulous with maintenance and had received the starter upgrade and replaced coil packs, plugs and oil change at 75K miles (oil done every 5K miles). Battery in car was 2 yrs old. We've put ~3K miles on car with no issues whatsoever. He warned about flooding issue but we've been careful to always let warm up before driving or shutting down. Drove to work and then returned home in the evening and all was well. Got in car 2 days later and key fob wouldn't unlock door. Opened manually and tried to start but got nothing. No lights, no starter "click", no dash lights, maintenance codes.....nothing. Replaced battery in fob and car. Terminals are squeaky clean and all connections tight. Went to unlock door with fob and no joy. Opened door manually and tried to start with no joy. No lights, no clicks, nothing. It's like there's not even a battery in the car! Tried pulling ignition and starter relay then reinserted with no change. Thanks in advance and sorry for another post like this!