Power Door Locks Not Working problems of the 2004 Acura RL

I parked the car and turned off the ignition. The lights on the dash blinked right after turning off the car. I knew I had a problem because the door locks wouldn't work. I tried to re-engage the electrical system to open the door locks, but the car was totally electrically dead. I tried a couple more times to start the the car, but absolutely nothing. I sat in the car a couple minutes without touching anything. I tried once again to start the car and it worked. All the radio and nav system needed to be reset. This has occured 3 more times over 3 months. Each the same way. As I parked and turned off the ignition, it blinked and electrically failed. Last two times being only 5 days apart. So it's happening more frequently and closer together. I had my mechanic look at the car. He'd never heard of this problem and had no clue as to how or why it happened. He examined the whole electrical system and found nada. So far, it has not re-occurred 3 weeks after being looked at. Frustrating, concerning.