Had an issue with the negative cable n had to replace the bolt n nut. Since then its been making weird noises under the dash n under the hood even when the key is off. Sounds like something moving around under there almost but i know there is nothing. Also making buzzing noise every 30 minutes or so for a few then stops. Separate noises n 2 separate issues tho

 

Check the other end of the cable. Might be simpler to just replace the entire cable (since you had to replace one end, and that appears to be the only change since this problem started)

also make sure the battery connections are tight and clean.

 

Ill give that a shot. I actually have a brand new cable sitting around. Hopefully its the right length, if not off to the parts store i go. Cheap n easy check

 

Rattlesnake?

 

Rattlesnake chasing a mouse.