Cub Cadet RZT 42 clicks and Battery cables melting when trying to start

I Picked up an RZT 42 with a blown 17 HP kohler engine, I replaced the Engine with no issues.

When I tried to start it for the first time:

Handles in Neutral position, PTO off, braked on, etc. Upon turning the key I can/could hear a click from under the right panel (not the starter) after trying it a half dozen times and getting the same result click, click, click every time on turn the key to start I noticed the wires on the battery getting REAL hot and melting



Suggestions on what to look for???