My engine in my 97 540i blown up and i had no indication light to go off?

What is your question?

I was driving my 540i home and it all of a sudden lost speed and i pulled it over and had it towed to the bmw dealer and they said it blown the engine. i had no lights or bells to go off and let me know what was wrong. Now my warranty won't pay for it because they said i ran it hot! i had no ideal the car was hot because the temp. gauge was at the normal range and it was full of water. help me please. i need my car fixed and they won't fix. i need advice. HELP!!!!