Not starting after replacing MAP sensor?

For further info, I never used this site before, I first replaced the ECU with another used one that was programmed to work on mine because the first one seemed to have stopped working completely. I replaced it because I needed to see if it would correct it. It seemed to have corrected it because it started and I drove it, which the first one wouldn't start it at all. I then also decided to replace the MAP sensor, which also controls everything, to make sure it was not that also. The one they gave me would let it run for 3 seconds then shut off. I tried it many times and then it shut off and wouldn't turn over at all. I reinstalled the initial one I replaced which worked. Now both do the same thing. It won't turn over at all. It is as if the MAP sensor ruined both the ECUs unless someone can tell me something else is now causing it. Remember, as I said, I replaced the original MAP sensor that used to work, with the new one. Motor is now completely not working with both.