Yeah, it was definitely the intercooler, I don't think Microsoft repair lied to me. They said that there was a power surge and told me to look at where the intercooler plugs into the power cord hole on the back of the 360, there were indeed scorch marks there from where the Nyko Intercooler power plug overheated. They said that because the intercooler draws power from the console power supply instead of having it's own power supply, it can cause major issues due to the amount of power that goes through the power brick, through the intercooler, and into the system, Nyko build quality wasn't great and could cause a short as that current passed through it. Nyko was actually sued over it as I recall because they didn't disclose to people that Microsoft recommended against using their Intercoolers, and they were forced to put a disclaimer on later models that they made, that you would be using the intercooler at your own risk of damage and warranty voiding.
My bro's Intercooler plugs in pretty snug. I could see an issue if the user didn't push hard enough to ensure a solid connection. Pretty hard to believe it was that big of a manufacturing tolerance issue for Nyko that they didn't realize it until there was a ton of products sold to consumers and didn't recall them. Could be, just kinda tough to believe.
Mind you, it's tough to believe MS themselves would launch XB 360 as they did and ignore the RROD as long as they did. Yet MS eventually made good on those problems, so why not Nyko? Business is business I guess.