Are you able to access the phone through ADB?
If yes, run: adb reboot download, and this should put you in downlaod mode so you can odin a new firmware.
If no adb access, Does odin recognize the phone?
If yes, you should be able to odin a new firmware.
Make sure when you flash the new firmware you are using the correct rom for your device. ie: from your post you have a GS2 I9000 which is not the same as the GS2 SGH-T989.
you would use roms from this forum: http://forum.xda-developers.com/forumdisplay.php?f=665
If you are unable to flash a rom you can always purchase a download mode jig to get you into download mode if you have not Hard Bricked the phone. If you have Hard Bricked your phone there are a couple of sites that do Jtag repair to unbrick your phone.
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