Hey Dave - I have one those cards too!
Anyway, I just checked the Adaptec website and there is a newer version of the required driver available. You are currently using version 1.0.2 when you probably should have been using version 1.1. However, don't bother downloading it as the download web page states this:
Notes: The version 1.1 driver is embedded in Mac OS X 10.2 and later, there is no need to download and install this driver if you are running Mac OS X 10.2 or later.
So I imagine that's why your computer wouldn't boot after you installed the version 1.0.2 driver - driver conflict. If the installer doesn't come with an "uninstall" option, you will need to manually remove the version 1.0.2 driver in order to restore the OS X. (Navigate from your "hard drive" - System folder / Library folder / Extensions folder - and find the file. It will be called something like: "Adaptec2906.kext". Right click (or "control" left click) and choose "move to trash". The computer will ask you to Authenticate the action with your system password.)
As for why your SCSI card isn't working - well that's not looking so good. Because the correct driver is built into Mac OS X 10.2 Jaguar - your card should have been working properly - or at least showing up in the system profiler. Since there are no downloadable files to re-flash the firmware - we can only try so hard. Should none of the below work, I would contact (email) Adaptec, tell them what happened and ask for help. (Refer them to this thread on macosx.com even.)
1. Shutdown, disconnect SCSI cables from Adaptec card, disconnect power cord, and open Mac up.
2. Touch the metal side of the Mac case with both hands to rid yourself of electrical discharge.
3. Pull the Adaptec card out of its PCI slot. You will need release the screw that holds the card in the slot in order to remove it. (When you have it out, inspect it for obvious damage - especially the contacts at the bottom.) Re-connect card. If you can, relocate the SCSI card to another PCI slot when you put it back.
4. Press the CUDA reset button on the motherboard. (This is probably what you should have done after the blackout instead of re-installing Mac OS X.) The CUDA reset button is a little silver metal button located on the motherboard - often near to the CPU. (You may need to use the end of a pen to push it down.) Hold it down and count to three!
5. (Wait a minute) Reboot and see if card shows up in profiler.
6. If yes - re-connect SCSI cords and test scanner. If no - contact Adaptec.