Dead Canon 420ex?

[geekyrocketguy]

I was using a 420ex yesterday. When I took a photo it emitted a very loud pop when it fired...I checked it, but it wasn't hot or visibly damaged. It made loud pops for about 3 photos, then stopped firing. It audibly charges, the pilot light works, and the head zooms normally, but the flash just won't fire. It doesn't matter if the flash is on or off the camera.

Is the flash totally dead? Did the bulb part blow? Does anyone have experience with repairing this problem?

Thanks!