I once worked late night security at an urban construction site where they were building new upscale apartments. I had an incident happen on 2 different nights. The first alert I had was a beat-up old radio turn on all by itself in the middle of the night. It was blaring old style Mexican fanfare music. After a complete look-around, I found no intruders, then I unplugged the radio, I just assumed it was an electrical short in the radio because it looked heavily abused by weather and misuse. A month later, on Halloween of all nights, I was patrolling the same grounds inside one of the buildings. I heard the sound of a radio turn on, blaring the SAME old style Mexican fanfare music. I thought it was the same thing, but I yelled for whoever it was who turned on the radio to exit the property or get put in hand-cuffs. I realized I left my cell phone in the car, so I ran back to my car so I could call the police in case there was someone trespassing. I got my phone and sprinted back to the building. I was listening for the radio, walking the hallways cautiously in case I got jumped. I was walking toward where the sound was coming from. And then the radio turned off! I was freaking out. I quickly got out of that building and radioed my supervisor to let him know what happened. I'm convinced that place is haunted. My co-workers have said that they've also heard creepy sounds in that building as well, others didn't believe me. I've gone back in since then and I've heard voices murmuring in the dark. Even though most will say it's unlikely to be haunted because it's a brand new project being built on a land where no building existed before, I'm convinced it is. Construction companies are known to find ancient native artifacts when they excavate the land and keep it secret. Because they don't want to lose all that potential money to a heritage protection organization who will takeover their property, halt the construction, and give them nothing in return. My guess is that it was a native burial ground, or a location of an Indian battle. To this day, I refer to this incident as the Phantom Radio
Ever seen a touch activated lamp cut on all by itself? Probably something similar, electromagnetic interference interacts with the electronics in the radio and triggers the circuit that turns it on.