We are clueless on 2002 Nissan Altima

We bought a car from a lady and she had just took it to Nissan and had all the recalls done on it and we got it home and it would not start. we then had it towed to our local machanic and the diagnostics said it was the crank sensor so he put one on it. Then he took it to the nissan place and had them reflash the computer. It would start up sometimes but not all the time. When he took it to the nissan place the instrument cluster was working but they said it stopped. No one really knows what is wrong with the car so we are afraid to do anything. They said it could be the cluster or it could be the complete wiring of the car. Sense a cluster could not be returned we have done nothing to it. They said the wiring could cost several thousand dollars. I guess my question is will an instrument cluster cause vehicle not to run? Any information would be very helpful.

Asked by for the 2002 Nissan Altima