BMW 325i 2005 automatic

Here is the story, came back from war and needed a job driving so I purchased this car on Craigslist . I spent 4500 on it and drove for 3 days and the engine went out.I purchased a used engine on eBay for a 1000.00 that was the exact engine type for my car. I had a shop install the new engine for me for 1500 dollars. After install they could not start up? I didn't gave another 1500 to fix so here it is . The engine is complete and installed but I cannot start it. It turns but does not start? So, I also have the original motor complete that you can keep also. I have all receipts to prove the story . There's a lot of rotten people out there.