What fuse or blown component would prevent starting?

[Theom]

I was trouble shooting my no-spark condition on my engine and I think I blew something. I performed the following procedure to test the coil:
1) Inserted a spark plug directly into the coil wire end that would normally connect to the distributor cap.
2) Placed spark plug tip against manifold riser bolt to ground it
3) Attached a 16 gauge wire to the negative post of the coil
4) Turned battery and key to on
5) Scraped the other end of the 16 gauge wire against a bolt head on the exhaust manifold
6) Result: The spark plug generated spark

Then my boat alarm that comes on after about 10 seconds of the key being on alerted and I scraped the wire again to see the spark again, then power suddenly cut out. Now the boat no longer turns overs.

What could I have blown from this procedure? After this happened I used a voltmeter to test power at the positive post of the coil with the battery and key in the on position and I'm no longer getting power at the positive coil post. Prior to the above procedure I was getting 12.7 volts at the battery and 12.0 volts at the coil positive post. Now I get 12.7 at the battery and none at the coil.

Engine: Mercruiser 7.4L
Engine Serial #: 0C662618
Boat is a 1989 Maxum

 

[Fun Times]

Check for 12v at the red button 50-amp circuit breaker on the engine and also at the orange wire off the back of the alternator stud. Item number 19 and may as well check 27.

https://www.mercruiserparts.com/bam/subassembly/31920/959/70

https://www.mercruiserparts.com/7-4l-bravo-gm-454-v-8-1988-1991-0b7711

Also there should be a 20 amp fuse either near or the back side of the ignition key switch. Make sure the safety lanyard switch at the control shifter is in the run position and in neutral position... Wiggle the main cannon wiring harness plug at the engine just to see if you get power back too.

Do the gauges at the helm power up at all now?

 

[Theom]

Check for 12v at the red button 50-amp circuit breaker on the engine and also at the orange wire off the back of the alternator stud. Item number 19 and may as well check 27.

https://www.mercruiserparts.com/bam/subassembly/31920/959/70

https://www.mercruiserparts.com/7-4l-bravo-gm-454-v-8-1988-1991-0b7711

Also there should be a 20 amp fuse either near or the back side of the ignition key switch. Make sure the safety lanyard switch at the control shifter is in the run position and in neutral position... Wiggle the main cannon wiring harness plug at the engine just to see if you get power back too.

Do the gauges at the helm power up at all now?

Found the fuse that connects to the start switch and it was blown. Had a 15amp in it, so I put the 20amp cigarette lighter fuse into it and now everything lights up again and it turns over. Thank you for getting me moving forward with this repair.

Not that it matters now, but the alternator and #19 and #27 components and positive wire on the front of the 50amp fuse component all had 12.8V readings prior to checking the fuse.