Really, there is nothing to this at the current time. Just a battery holder and two wires.
I just can't justify why this battery nearly melted on me.
It should be a straight forward electronics troubleshooting effort to figure it out. What tests have you tried to use so far? You don't need to 'justify' the reason for the high heat, just normal electronics troubleshoot will make the final answer very clear of the what and the why for the symptom you have.
Lefty