One time when changing out a mobo I forgot to remove an extra standoff where there was no hole on the new mobo. LEDs would come on but system wouldn't boot. It was a bitch to troubleshoot but once I finally figured it out and removed the offending standoff, problem was solved with no permanent damage. So your mobo may be fine. On the other hand, my PSU didn't "pop" like yours did so maybe something more extreme happened in your case ... hard to say.