This is probably not Canon specific, and I hesitate to say anything before this gets fixed under warranty. Disclaimer: I'm posting this for an associate, and nothing I write here necessarily reflects my own experience with my own equipment. With one EX-430ii already in VA for warranty repairs, its newly purchased replacement likewise suffered a quick, identical death after shooting 56 shots at 1:1 power in 130 seconds. The flash just stopped working. The LCD panel was blank, even after changing to known good, charged batteries. The batteries were warm to the touch when they were taken out to be replaced. There was a slight but noticeable "electronic" type smell when the battery door was opened. The batteries are PowerGen NiZn AA. The other flash died in an identical manner, under very similar use and conditions. (Indoors, nothing at all strenuous except perhaps the cycle rate.) Consider this a strong warning about using the PowerGen NiZn batteries in Canon SpeedLites.