Brake Light On problems of the 2016 Lexus RX350

First problem with electrical was when the navigation screen went completely blank while driving during broad daylight. Don't know the date of this incident. Thought it was a reboot by enform. Thought nothing about it. On 12/21/2017, check electric brake warning light came on when I started my car in the morning after it had been sitting all night. Took into the dealer. Dealer could not find any problem with it or any error codes indicating any problem. They reset the error light. On 4/23/2018, I stopped for a stop sign at about 12:30 pm, nothing happened when I tried to accelerate at which point I noticed I had no lights on anywhere on my car. It was dead. I was stuck in the middle of the road and was unable start it after a couple of tries. Called for emergency service, let Lexus dealer know my car was going to be towed to them, and sat for about 15 minutes when a gentleman came along before emergency service rep got there. He was able to start the vehicle. Took to dealer and was told after 4 days that they could not recreate the problem. Am now driving it, but afraid something else may happen.