certainly leaning toward dried power supply. When you turned the breaker back, or even when it popped you might have had a power surge
Some power supplies will offer limited function if they are damaged, allowing fans to spin (12 volt rail still works), or motherboards to beep or lights to flash (3 volt still works), but if the 5 volt rail goes, your power supply will not function (video cards used to use 5 volt rail, but I think only the power switch still does, irony of irony)
Some power supplies have a circuit breaker built in, so check the back of the PC.
Also, check to make sure someone didn't hit the rocker switch on the powersupply.