Hey guys, I got my head scratching on this one...

So, I bought this 08 6MT Z33 @104k miles, about 2 months ago from a private party. It has a ton of really bad and cheap mods that I'm slowly saving and either replacing with stock parts or proper versions of those mods.
About 2 weeks ago, it just stopped starting all together.
When I got it, it had no front drivers turning signal, and the horn didn't work. I took it to a shop where they found the horn fuse was blown, the horn wires were cut right next to the horn, and because the car is so damn low, the fender liners were removed and the wheel rubbed away at the wires to the turning signal... lol... Also, the clockspring had gone off.
On my way to the shop, I noticed it missed a couple times after I went over a train track...slowly...cause too low. On accel, it missed, but resumed. They fixed those wiring issues and fuse, and I was on my way back. Cranked right back up, and right before I got home, I noticed it missed again. No CEL, tho. The next day, literally that next morning, I tried to crank it, and all the lights dimmed like it's going to do something, but, nothing. Nothing at all. No sounds, no clicks from the starter, nothing. I push started it and it came right back on. Cut it off, turned back on with the key. I put my code reader to it to see if there was anything at all. I ran every single scan I could to find something, anything, but everything is in spec, no codes whatsoever. Sooo, I cut if off, went inside for 30 minutes, and it turned on again, drove to my doctors appmnt, and it didn't start after the appmnt... Had to push start it in a tight parking lot. Took it home, cut it off, tried starting again, and it wouldn't start. I read that a bad clockspring can cause issues like this, and I did need a horn and airbag anyways, since this is my first sports car, and I LEARNED that it didn't come with traction control...oops. I replaced the spring, and nothing still... Horn works now, tho.

I don't THINK it's the starter... A bad starter should at least click and crap itself. It worked perfectly and then just stopped. I don't know if it's a sensor, but I'd assume I'd have some sort of code, let alone a CEL. It DOES have an aftermarket Clifford G5 Avantguard 5.1 Security System, but I jumped the starter and ignition wires before the receiver and it doesn't do anything, and my clutch safety switch feels very firm and I hear a click like a completed circuit when it's depressed. When it did run, I didn't notice any missing or hesitation on the last ride to and from the doctors. Why would it push start then but not now?

I have a fair understanding of mechanical things, but when it comes to wiring, I'm sort of a deer in the headlights, and tend to get overwhelmed, which is why I took it to a shop in the first place for the wiring issue.

If anyone knows where I should at least start... Worst part is, she was supposed to be on coilovers by now and I spent my whole weeks vacation that was supposed to be me enjoying my car, trying and failing to fix it myself.