New to the forum thanks for looking

I recently had too much corrosion on my positive battery terminal. While cleaning I noticed the bracket that goes around the terminal was beyond repair. I purchased a new one but could not get the nut on top that connects the old one off.

Trying to muscle it off I broke the plastic harness that connects to the vertical portion and now want to replace the assembly from the wires just below this up. The dealer only sells the entire wiring harness at a price of 1000+. Does anyone know of a alternative or is it safe to just cut the top bolt and nut off and leave the rest unprotected.

On a side note I know it sounds bad but I know a lot of cars were totaled in the storms on the east coast I would assume I can find a scrap yard that may have some Mazda 5 for parts since I live outside of Philadelphia.