car will fire but not start

What is your question?

I knew battery was going bad and tried to make it to payday to get new one. One day stopped somewhere and when I tried to start it it was dead. Some strangers offered to give a jump. I was in car to turn it over and the strangers hooked up the jumper cables. It smoked when i turned it over. My guess is they connected it backwards. I went an bought new battery and since then it will fire but not start. have not been able to hook it up to a diagnostic machine, but have been told its my main computer and it will cost about 900 to fix. I am hoping this is wrong and there is a simple fix. any suggestions or info would be appreciated. I love my car and miss it. this happened end of july and its been stored in barn since.