I need help, shorted wire, fire, fixable? Options

[6strngs]

well, as some of you know I pulled my transmission out to replace the rear main seal. Well, I was doing the final stuff today, and I go to put my battery in, and I put the positive on, but as soon as I try to put the negative on, it sparks, alot. it usually never does that so I was a bit concerned. I went and asked my dad who is an electrical engineer with a PHD, if anybody knows anything about electricity, it should be him. anyway, he tried, and it sparked, but he just forced it on and it stopped sparking... hmm... he said it probably just had some electrical current built up it needed to ground and it'd be fine now. so I go to start it up and... nothing... some noise that sounds like a motor whirring, but that's it. we're trying to figure it out, knowing it's probably something electrical, when I see that my friend who was helping me hadn't tightened down this one nut that is for that cable (ground cable, I thought) that has a plastic cover over it that goes on the started. so I go to tighten it, and as soon as I do it starts sparking, so I let go and hit the ratchet till it comes off, but then it starts to glow red and smoke in that area, so my friend is trying to pull the battery cable off while I'm frantically searching for a fire extinguisher. well, I ended up burning my hands trying to get the negative cable off, and eventually I pulled the post right out of the battery. anyway, now all the wiring in the area is all charred up, but it's only in that area, I don't know how much damage has been done and I don't know if it's fixable or how I could go about fixing it. I'm going to include some pictures, but could somebody tell me if this is fixable and how hard it's going to be?

I'm kinda just happy to be alive, my dad said that there was probably enough amps flowing through that circuit to kill me about 100 times over... but it still sucks cause now I'm still without my celica and I don't even know where to start this time...

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