Hearing clicking noise in driver door, dash and passenger armrest. All this while car will not start?

We bought the car used one year ago with 24,000 miles. Car fax checked out fine. Two months ago while driving I noticed the radio going on and off. Also the same time the door locks unlocking and locking. Thought it was strange and kept driving. Well last week the same thing started to happen again, this time I pulled over put the car in park and turned it off. As soon I did this I started to hear a clicking noise in arm rest and the car would not start! It was completely dead. 2 min go buy the clicking stops and the car turns on. Runs fine after that, like nothing ever happend! Untill about 2 hrs later it did it all over again! It's been a few days and it hasn't happend! We got the car checked out, mechanic said everything tested fine? Could it be a electrical problem? Pls help! I'm starting to think this car is possessed!