If your starter motor is still not engaging, don't go fiddling around with your EMS. The EMS has nothing to do with the operation of the starter motor (exception - see my comments on Na2 cars at the end of the post)! The more unplugging and plugging stuff back in you do (especially on older cars) just creates new potential failure spots from weakened connections.
I have attached a .pdf document showing the wiring diagram for the starter motor (encircled in red) for the early model years (I am guessing that you have an Na1 model). As you can see, it is pretty simple. The only item that I did not mention as a possible failure item in my initial response is the starter cut relay (I am not aware that this has been a common failure item). As you can see from the wiring diagram, if the starter cut relay does not get energized, neither the starter motor solenoid or the fuel injection main relay get power during start up. The starter cut relay gets +12v from the ignition switch and is grounded through the clutch pedal interlock switch and then the security control unit (black/yel wire on the security unit).
I have also attached a .pdf of part of the test procedure for the security control unit . As you can see from the test procedure, if you ground the blk/yel wire on the 22 pin connector at the control unit (make sure connector is removed from control unit!), the starter motor should crank. Be aware that the engine may start since the key has to be in the start position and the clutch pedal pressed in during this test. If it doesn't crank, then the problem is one of the following: a faulty ignition switch, starter cut relay, clutch interlock switch, starter motor / solenoid or wiring to same (most of the stuff that identified in my initial comments). If the starter motor does crank over then the problem is with the security control unit (have a fun time diagnosing that one - lots of wires and switches!).
If you can get the starter motor to operate and the engine still does not start, then you have moved your problem from the starting circuit (a relatively simple thing to diagnose) into the engine management system and its associated stuff (a potential world of hurt!).
The diagrams I attached are from the '91-'92 service manual on Dali's site. You might want to check the manual for your specific year to see if there were any color changes to the wiring. If you have an Na2, then you should definitely be checking the service manual; although, I don't think there were any material changes to the starting circuit (The immobilizer circuit in the EMS does get tied into the starting system - the fact that you have an aftermarket EMS makes me guess that you don't have an immobilizer)
