Melting Plastic... Not the kind I wanted

I have a ramps 1.4 board that came with the folger tech 2020 kit. Everything has been good for the couple prints that I have been able to make, no major ramps issues. I felt like the bed was heating kind of slow but have no idea what a normal time would be. When I was setting up for a print and the bed was being heated I saw smoke coming from the ramps board of my printer. I shut off the printer and just left it for the next day. After coming back to it I noticed that my bed wasn't heating at all. I would heat the bed, but it would only raise a couple degrees if anything. I come to find the photo attached (sorry for the crappy picture). I don't know how that happened. I know that the i am unable to get to one of the heater connectors on the ramps board so I am looking to replace the board with one that I found on amazon.

I guess my question is if anyone knows that happened and how can I prevent it?

Thanks!
Schmuck

Loose connection. Either you didn't tighten the screw enough or you tinned the end of the wire with solder and the solder flowed to loosen it. Solder shouldn't be used to tin the ends of wires going into screw terminals, it's too soft and flows under pressure.

I did have problems with the wires coming out, so it must have been a loose connection. I never used solder. I will really screw them down next board.

Thanks man!