Our Ford Five Hundred overheated ruining the engine. The only light on was the engine oil life 0%. Any idea why this caused the engine to lock up?

Either there was no oil in it , or something happen to the cooling system, but there are warning signs that you should have paid attention to, to shut it down before frying it.

My son was driving it when this occurred. He said the no oil dashboard light was not lit. I have had a ford blow its head gasket before. Could this have caused it?

Yes but again there are warning signs like a bunch of white smoke out the exhaust, milky and over full oil due to coolant getting into the oil, and or the cooling system over heating. If coolant had gotten into the oil, yes this would lock the motor up if it was still driven.

This will be a costly lesson for my son. This actually happened to me about 15 years ago with another ford that blew a head gasket. I began to lose power driving on the interstate prior to overheating. I now know to check the temperature gauge when that happens. I am glad you posted your story for others to learn from our mistakes. I know to always check the temperature gauge when something appears wrong. One can not rely only on the dashboard warnings.

I found a worn out camshaft drive on an 05, Looks like a DESIGN FLAW