2009 Chevy Malibu is dead, no crank, no clicking sound, no lights turning on inside. Just completely dead

I need help. My 2009 Chevy Malibu was working fine, the next day I was going to turn it on, it didn’t. There was no crank, no clicking, no lights inside turning on. Nothing, just dead. I have replaced the battery, the alternator and have checked the fuse box and relays and those are working fine. What can it be? Any input is greatly appreciated!!!