Did the dealers maintanence work kill my 2008 Dodge Caravan?

We had our 2008 caravan in to the dealer for an abs sensor module replacement.  They of course found many other things to charge us for.   They found a leak in the radiator that we replaced and also persuaded us to do a fuel injector flush and cleaning.  1700 dollars later we got the car back.  The day following our visit the car died in a busy intersection.  When trying to restart it made loud knocking sounds and would not restart.  We had it towed back to the dealer and it took them 2 days to say that it could be the timing chain or a thrown rod.  It is too coincidental that we would have the car back for one day just to have it die on its own.  Is it possible that maybe the fuel injection flush could have damaged them so they were stuck open causing the engine to hydrolock and throw a rod? The dealer tells us they still have no idea what went wrong.