New to tuning. Can a readable computer cause a car to not start?

I am working on a Jeep Grand Cherokee that doesn't fire to the spark plugs. Is there something in the computer that would cause that because all the wires seem fine? The computer seems fine/not broken since I can read it, and I didn't see anything in the file that would not cause the car to start. Am I missing something or is it just not the computer?

of course there is

if you hold the pedal to the floor and hit go what happens to the spark?

The customer took the car, so I couldn't test that. Thank you for the reply though.