I KNOW THIS IS DETAILED, BUT PLEASE READ!!

Background info (ALL HISTORY ABOUT THE ISSUE): The guy before me installed an aftermarket security system, and also rewired the tail-lights to a button, to bypass a fuse, where he said that the dealership quoted him ($1000) to repair a bad BCM, which I tested and works perfectly, so I am about to finish installing a new body harness, b/c the taillight wire melted, and melted some of the wires around it. When that wire melted, my cars lights interior lights started acting up, also the ABS, VDCL, SLIP, and check engine lights turned on. I got the code pulled, and there was only one that said (bad ECU), so we cleared it and it never came back on, so the ECU should be fine. Also, the car would stall out and burn the ignition fuse when I turn on the tail lights via rewired button. Also, I want to remove the aftermarket security system, b/c the wires are not correctly insulated, which may have caused the short. LASTLY, I noticed my rack and pinion leaking, pretty fast. (My thought is this may have caused the lights to turn on in the cluster and maybe fry my shitty body harness)

QUESTION: After removal of the aftermarket alarm system, and new body harness, am I safe to turn on the car and lights, or should I replace my rack and pinion before I start it, just in case it might have caused the short.

Interested in pictures? (Look here): https://g35driver.com/forums/engine-...-diagrams.html