I have a 1993 Geo Prizm LSI, that cranks, but will not start, and has no spark. The problem began as a cold engine hard starting problem, but after I replaced the distributor with a rebuild, it stopped starting at all. The rotor, the cap, the plugs, and plug wires are new as well. The battery is new. I replaced the ECM with a used unit, and still no luck. Any Ideas gents?

Sounds like the replacement distributor rotor wasn't in the same position as the old rotor in the one you took out. The distributor is powered by a gear meshed to the crankshaft and the rotor has to be in the right position (#1 cylinder at TDC) to fire the #1 plug. Use a compression gauge inserted in the spark plug hole to determine when the piston is TDC.
When the piston is at BDC there will be no compression. The piston travels twice for a complete cycle once at TDC and another at BDC. Hope this helps.

Are you sure you got the dustributor in the right tooth? Check timing using procedure at link below. Or, maybe you got a bad rebuilt. Here are some tests to check it out:
1993
See Figures 6 and 7

1. Check for spark at each spark plug with a spark tester. Check at least 2 plug wires.
2. If spark is only detected at some plugs, check for a faulty distributor cap or rotor. Also check the spark plugs and plug wires. Replace, if necessary.
3. Measure the resistance of the distributor connector C1 when cold, between terminals 3 and 6, using a digital voltmeter. If the camshaft position (CMP) sensor resistance is not between 185-275 ohms, replace the distributor housing.
4. Measure the resistance of the distributor connector C1 when cold, between terminals 2 and 5, using a digital voltmeter. If the camshaft position (CMP) sensor resistance is not between 370-550 ohms, replace the distributor housing.
5. Measure the resistance of the distributor connector C1 when hot, between terminals 3 and 6, using a digital voltmeter. If the camshaft position (CMP) sensor resistance is not between 240-325 ohms, replace the distributor housing.
6. Measure the resistance of the distributor connector C1 when hot, between terminals 2 and 5, using a digital voltmeter. If the camshaft position (CMP) sensor resistance is not between 475-650 ohms, replace the distributor housing.
7. Measure the air gap between the signal rotor and the camshaft position (CMP) sensor. If the air gap is not 0.008-0.016 inch (0.2-0.4 mm), replace the distributor housing.