My Sons Hobbywing a XR8 Plus had the capacitors become un soldered which he soldered back on. After putting it back on the track and running the switch started smoking. Does anyone have any ideas what would cause this ????

shots in the dark here, but bridged capacitors. bad capacitors. bad switch.

The esc is most likely done. When the caps came unsoldered, that was probably due to a short or overheating. I had a switch smoke once, and after changing the switch, the esc got VERY hot VERY quickly. So, I did the replacement thing through HW. I suspect that is what you will need to do, as well.

Yeah, once you let the magic smoke out, it never works the same again.

If the ESC got hot enough to melt the solder on the capacitors, then something was already wrong. By default the ESC has ESC thermal protection turned on, which should have shut it down if it was simply overheating. But it sounds like it developed an internal short that caused it to get that hot.

Thanks guys for the bad news.