No Spark on a Kia Spectra 2000

It's been 1 month and my Spectra has not started. It cranks but does
not start up. The is no Spark coming through the plugs. I replaced the
Crankshaft Position Sensor and also the Camshaft Position Sensor but
that did not do anything. I have tested plugs/wires and both coils and
even used spare parts yet still no spark.

A friend who is a mechanic insists it's the ECU, so I took it to a shop
who unfortunately left it worse as now the Car doesn't recognize the
ECU and the computer overheats. It is now in another shop but I won't
get it back soon. I ordered an extra used ECU and I should be getting
it in tomorrow.

If when I get the ECU back the car still doesn't start, I still have 2
possible causes to review. 1 is the Immobilizer unit. it seems to be
working as the light on the dash indicates when a bad key is inserted.

The second thing is that perhaps my Timing belt skipped a tooth. If so,
would that cause a No Spark situation? I wouldn't think so especially
when I once retarded the Exhaust cam (don't ask why) and that is where
the Camshaft Position sensor is at. The car started, but ran roughly.
So having both sensors in sink was not that important in getting a
spark.

Also, if the belt skipped one tooth, that would mean that the Intake
and exhaust cams would be retarded, not advanced, right? Is it possible
for the CAM to skip one tooth and leave the CAMS advanced?

Thanks