I would start by calling PIAA and explaining the issue. I'm sure that they have heard of a similar issue (flash on, then off) and should be able to give you ideas of where to check first.
If they flashed once then off, maybe you blew a fuse due to a short. Make sure all wiring is correct (not reversed, not exposed, all of the obvious things). If they flash on, then off everytime then this wouldn't be the case. Make sure all connections are seated correctly and the bulbs are correctly installed.
Go through all the most obvious things as it is usually something that was overlooked.