Here's my timeline of events-
I kept having issues with my power steering, radio, or lights intermittently going out while i was driving. My brother unhooked and rehooked the battery and it was fine for 6 more months.
It started happening again so i took it in and got a new alternator.

But i was still having the issues with power steering, radio, lights intermittently going out while driving. When i had the alternator replaced they told me the battery was low so i took it to AutoZone (purchased in 4/22 so still under warranty).
The lady there had me start my car and she said the battery was running at 100% (but wouldn't it be, since it was running and being powered by the alternator?)

Anyway, i cleaned the battery terminals, hoping it would help.
Threw an arc (sigh), then i couldn't get the car out of park. Checked fuse #24, then went down the rabbit hole thinking the fuses were burned at the prongs and the prongs were stuck inside the fuse box, but later learned that they were low-profile fuses and were fine.
Next (after checking forums) i checked the battery fuse terminal assembly and discovered fuse #3 was blown, ordered a new one on eBay, installed it, then went to start the car, and it tried to start, then nothing. Brake pedal went stiff, and i couldn't even get dash lights to turn on with the key.
Removed the battery, took it back to get it checked at auto zone, it was bad (probably because of prior bad alternator). Still under warranty, got a new battery, installed it, still get nothing when i turn the key. No clicks, no lights, nothing.
I think something blew when I tried to start it with the bad battery.

But what?

I'm a novice, i don't really know what I'm doing, but I'm trying not to spend a million dollars to get this fixed so I've been trying to follow what i find in the forums, but i think at this point i need to take it somewhere.

Any ideas of what might have blown when i tried to start after installing the battery fuse terminal assembly?

I'm trying to remove fuse #60 (main) but the screw is so tight on there I can't get it loose, and I'm afraid I'm going to strip it.

What is it going to cost me to get this fixed? What can i do to save this car?

 

When you say "It threw an arc" what do you mean? Did you accidently touch the negative battery cable to the positive battery post when reconnecting it?

 

Yes I must have. I think that is what blew the #3 fuse in the battery fuse terminal assembly.

 

If you touched the negative cable to the positive post of the battery then you probably fried the ECU.

 

The saga continues... had it towed to a different shop. They said everything looked ok, I didn't tighten the battery enough. They tightened it and it started right up. Well I got it back and the battery (brand new) light was on. I drove it back to the shop and it stalled out then I got there. They determined that the alternator (brand new) was bad. SO they charged up the battery so I could drive it to the place where I got the alternator installed because it was still under warranty. They replaced the alternator (again) but it was still not charging the battery. They told me to take it to a dealer because it is beyond what they can do.
So I took it to the dealer to have the full electric diagnostic done. They are just coming back with yeah the alternator is bad. But I am not satisfied. I don't think they have checked the ECU. They are gone for the day and I am feeling frustrated that nobody wants to really look into what is wrong with my car.

 

By the way, I didn't physically touch the negative cable to the positive terminal, but there was a spark from one side to the other.