1990 Mazda RX7 Mazda RX7 cranks, but doesn't start up!

Good day. I have a problem with this car related to the electrical system for what I hear.
I turn the key, the car sounds like its going to start, but it never does. Its not passing gas or something!
A mechanic says he tried every test related to engine problems and he thinks my car has a problem with some electrical issue, perhaps the car's computer its faulty, but he doesn't know for sure.
My car has to be sent now to another car specialist, because he can't work on electrical issues.
The battery its brand new and the spark plugs.
Could you help me determine what can be behind this issue?
Is it really electrical? Your expertise will be appreciated to help me get my car back to normal without being ripped appart with all kinds of mechanical repair bills. Sincerely. Marie.