Car "died" today. Nothing electrical works. Not even key less entry. Not a dead battery problem.

While driving the radio started to go on and off every few seconds. Later dash lights that only show during ignition started going on and off. Then engine started running roughly and almost stalling at idle. I pulled into a parking lot. After turning the car off, it would not start. Nothing electrical would work, not even key less entry. Previous to today the starter was cranking with no hesitation and everything ran perfectly with no signs of any problems.

Could it be as easy as replacing the main fuse or does it sound like something worse like the computer "brain" going bad? What is best way to get this checked without getting ripped off. I am not a mechanic and want to be able to defend against unneeded repair bills.

Thanks!

Eugene