Chrysler Repair: Car court :-(, chrysler sebring, radiator cap

Question
Over the winter my car would not start after a windy cold night(chrysler sebring 03).  Car was towed to a local mechanic who did all diagnostic checks (and documented it) and replaced the battery and car worked.  I picked the car up at closing time that night and parked it in the garage port.  Not as cold of a night.  The next day I got on the interstate and was driving about 20 minutes when car overheated and stopped working.  I had the car towed to the nearest dealership/mechanic.  There they found the car was missing the radiator cap and there was no fluid in the car.  My question is:  if you were the first mechanic who towed a dead car in not knowing what was wrong because it had been cold out the night before (it was December), before you knew it was the battery--would you ever remove the radiator cap to check the fluid or pressure to know what was wrong?  Also, could driving at 5:30 that night just a few blocks to my apartment and about 20 miles the next day cause the fluid to blow out and the car to overheat?  The second mechanic has it documented that the car came in with no cap (and hadn't been broken off) and the fluid was out of the car.  The first mechanic (who swears they didn't accidentally leave the cap off) has it documented that they checked the coolant in my car.  The second mechanic tore the engine apart and saw there was no problems with the timing belt or anything else with the engine.  There was no pressure or spark.  I've talked to some lawyers and they said I should take it to court for negligence and that I have a case.  I was just hoping for some expert advice before I go in there.  I'm a 25 year old girl and wanted to know the mind of a mechanic.

Thanks,

Answer
I am here to simply answer car questions  I can not get involved in a legal issue  and as for as that is concerned there is no way to prove that he did or did not remove the cap it would he hear say. if me  I would not need to remove the radiator cap to check for a no start no.