Possible Engine Damage?

I have a 2000 accord ex v-6. I let my nephew drive it and apparently he left it idling and went to a friends house. The car could have idled for as many as five hours but I am not sure how long because while walking by I noticed all the dash lights on but the car not running. When I asked my nephew he said that he had left it running and forgot. The check engine light was blinking. It had been on for a previous issue but not blinking.I think I would be less worried if I had found the car running instead of shut off for some reason. My questions are.... what could have caused the engine to shut off, what does the blinking check engine light mean and what possible engine damage could be done? I know these are tough questions but I need that car to drive on a long trip soon and would like to know what,if anything, to look out for. Also, the car started up and drove fine other than a slight whining sound coming from the engine. Sorry so long and thanks for any help.

So the CEL is flashing all the time now while running?

Fluid levels have been checked since this happened?

Assuming fluid levels were full and the fans were cycling properly, idling even for that amount of time shouldn't hurt anything. Autozone will retrieve your codes free, you could get the codes and have them reset, see if it codes again. If not, I wouldn't worry about it.

So the CEL is flashing all the time now while running?

Fluid levels have been checked since this happened?

Assuming fluid levels were full and the fans were cycling properly, idling even for that amount of time shouldn't hurt anything. Autozone will retrieve your codes free, you could get the codes and have them reset, see if it codes again. If not, I wouldn't worry about it.

... thats what dealerships say... don't worry about it lol.. he could be right about that it should be ok but maybe not. Hard to tell

i still wonder why it stopped running??