Melted wire in main panel? Help!!

[allturbocrx]

Hey everybody I was searching for answers and found this forum and hope you guys can help. I have had my hot tub up for about 5 years now and about a week ago the gfci kept tripping. I finally got to look at it and opened the control panel and found that the wire nut on the black wire was melted off and the wire was shorting on the metal box. I pulled that wire away and reset the breaker and it stays on but the metal part of what was left of the wire nut started to get hot so I shut it down. I thought about putting a new nut on it but figured I better look into the cause first. It says hydrospa on the panel and is a 4 wire tub. If anybody has an idea what might be going on please let me know. I am very much DIY and want to avoid a professional coming out if at all possible. Thanks in advance!

[goneaway]

You've probably come to the right place, however, your description doesn't really tell us much i'm afraid.
Wire nut on the black wire could be anything.

Maybe attach a few images and someone may be able to help.