The first thing you need to fix is the power supply to the coil. Most of the time the lack of supply is caused by someone cutting into this supply wire and installing an alarm/immobiliser, mostly in the area behind the glovebox.
To determine the exact problem, you need to start at the ignition switch. Remove the cover and test that there is +12v at the thick red wire. If there is no supply, you will have to trace the supply back to the battery to find where it has failed. (There is a fused link in the thinner of the 2 battery wires just after the battery terminal. It is covered in heat shrink so is not obvious. If it blows, it affects supply to most components, including the ignition switch.)
(It should be noted that it is best to use a 5w/21w bulb when testing for power as it will only glow brightly if the supply is good. A multimeter will show voltage even if the supply amperage is poor, i.e. through a corroded joint, so you will think you have a supply whereas, the minute you load it up, it will fail. Using a bulb eliminates this possibility.) I have an e30 front indicator unit I use which has long wires and and an assortment of connectors like croc clips for the wire ends to connect onto whatever I am testing.
If you have +12v at the red wire, turn the ignition on and test for +12v at the thick green wire. If there is no supply to the green wire, your ignition switch is faulty. If you have +12v at the green wire, go to the X20 plug in the engine bay, undo it, and test for +12v at pin 7 on the body loom side.
If you do not have +12v at pin 7, you need to find where the green wire has been cut between the ignition switch and X20. Dig around under the steering column and behind the glove box and look for an alarm/immobiliser unit. If you find one, cut it out of the car and re-establish the circuits that have been cut. Otherwise, run a new wire between the ign switch and X20.
If there is +12v at pin 7, and nothing at pin15 of the coil, either try to find where the break is in the engine loom, or just run a new wire from X20 pin 7 to pin15 on the coil.
Once you have ign power to the coil, switch the ignition off, disconnect the battery, and then disconnect the plug from the MCU (ecu) to test which plug goes to the engine speed sensor (CPS) and which to the cylinder ID sensor. on the no6 spark plug lead.
View of MCU plug.
Using a multimeter or other continuity tester, put one probe into pin 47 of the MCU plug and then test the pins of the 2 plugs till you find continuity. That plug will need to be connected to the engine speed sensor (CPS), the other to the cylinder ID sensor.
Reconnect the MCU plug, then the battery and try to start the car. Hopefully it will...
If not, we will need to go down another path of testing to find out what else is fubar..