Battery melted around post

[orlandois]

I have a 2003 EZGO which I've owned for one year. While driving the golf cart it simply stopped running and I couldn't get it to move. The lights still turned on but that was about it. I opened the seat to expose the batteries and found this as shown in pics.

This battery and cable in the picture is the only one affected. The other batteries and cables are fine. The batteries are Trojan T105 and were also purchased in 2003. Battery water was kept maintained.

The nut on the bolt didn't seem to be loose but I can't really turn it too much because of its present condition. I'm going to look for corrosion in the cable but wanted to check what other possibilities could cause this. Corrosion, bad battery plates, etc.

I'm assuming I need to start with replacing that battery....just wondering if I'm also going to have to replace the whole set of batteries.

Thanks