No-Start is caused by either No Spark or No Fuel. Do the easy checks first before replacing parts.
First, let's find which you don't have. The easiest and fastest to check is spark. Grab a spare spark plug and pull one of the spark plug wires on the trunk side. Insert the plug into the plug wire and hold it against the exhaust manifold while someone tries to start the engine. If it doesn't fire, your problem is ignition. If it does fire, the problem is fuel.
If it doesn't fire, swap out the ignition control module. If it still doesn't fire, swap out the ignition coil. As a last resort, replace the pickup coil or the distributor.
No Fuel can be a blown fuel pump fuse, a dead fuel pump, or a clogged fuel filter, or bad fuel pressure regulator.
Check the fuel pump fuse and the Inj 1 and Inj 2 fuses. Check all fuses. The Fiero has some funky crossover circuits that control things you wouldn't ever think of as being associated.
Remove the cap from the fuel pressure regulator. Try to start the engine, then standing back at arm's length, use something to depress the valve stem in the fuel pump valve. It should give a good shot of fuel. You don't want to have your face near it. If fuses are good but no fuel, you may have a bad pump.