There's not much that 'just happens' blown fuse, knackered components stopping post,
you could try just removing the jumpers all together, but ive never heard of jumpers falling off or chaning themselves, or the bios chaning.
You could try unplugging during a bios update if you have duel bios, swap the hdd sata cables around so it doesnt boot, remove ntdlr file off the OS drive, plug them into the wrong controller, use old cables udma 100?
It sounds that you might have some duff ram lying around, remove front cables for switches & leds
you could try just removing the jumpers all together, but ive never heard of jumpers falling off or chaning themselves, or the bios chaning.
You could try unplugging during a bios update if you have duel bios, swap the hdd sata cables around so it doesnt boot, remove ntdlr file off the OS drive, plug them into the wrong controller, use old cables udma 100?
It sounds that you might have some duff ram lying around, remove front cables for switches & leds

.
p out of them.
Doesn't matter if you have an anti virus on. They dont apear to work anyway.