I just got a phoenix DZBIS-112CII external flash for my Canon 550D. I have tried everything that I can think of to make it fire, without any luck. It came with four dead batteries in it which caused some corrosion on the metal battery mount, but I doubt that is what is not causing it to fire. I will clean it soon anyway. The flash has three lights on the back of it, one for TTL, one for ON, one for flash (lightning bolt), and one for OK. So I turn the ON switch on and the ON light lights up. I think the lightning bolt should light up when the capacitors have filled up.. not too sure though (It shouldn't take very long, right?). It never lights up. The OK never lights up either. My two ideas are that there's an internal problem, or a problem with the hot shoe leads. You guys have any diagnostics I can try?