Engine

Hi, my problem started before 3 weeks, when I was on way to work. My engine exploded and there was a big whole thru the engine. I took my car to service where mechanic said me, that i need new one and it will be cost about 700. He asked If I want new or second hand engine becouse second hand is cheaper, but i said that i want deffinitly new one. After 2 weeks when I came back for car he said that there is a second hand engine but very good condition and I paid him same money as for new one and it dosn´t work properly. car dosn´t start. And when i finaly jump it, there is blue smoke. So if can help can y just tell price of new engine if you know, becouse i know now that second hand engine cots about 200. Thanks