I think a short is highly unlikey since the system
worked for a period of time before breaking.

But I think He means a short on the Power supply
lead, not the A/C....

I have had the occasion or two where a staple went through the IR wire and created just enough of a short to let the system work long enough to trick me and then blow the supply. The fact that it worked at home all weekend is what made me think of this.