Which opening is stronger? Advice, please!?

they both need some work, and perhaps need to be a little less dramatic. personally i prefer the second one. i'd also recommend that for the second one, after the "flash"es, you put a period. for example: Flash. A deformed face screamed in agony taunted by flames. Flash. The charred skin, etc. that will make it more dramatic because i think that's the effect you're going for.