Hello, just registered to guide you to this page,
http://forum.xda-developers.com/showthread.php?t=1615058
Siyah kernel 3.1RC6 and BRICKED GALAXY S2 - xda-developers
There was a bug in an older siyah kernel, one which after doing a wipe on that kernel caused the emmc data to become corrupted. I was reading the thread for a while.
Check your downloads folder and see if you still have the zip file to see which version you were on.
If you read the thread, it goes on to say that several people tried getting their phones repaired via jtag flashing, yet that wouldn't even recover it. The only way to fix it was PCB/motherboard replacement.
Otherwise selling it on ebay as a bricked/broken/parts only phone should get a decent amount of cash to put towards a replacement.
I hope for your sake this isn't the case and you can fix it be other means
Also, don't worry about the cable not being an "official" one. As long as it has no damage, it would be fine. All the connections and wiring is identical, from a HTC, to motorola, samsung or even a cheap 99c ebay one straight from china.
Your best bet would be trying a completely different PC to do the flashing on. And make sure odin is run as admin.