I am not sure how the ICM got damaged in the process, but it is possible it may have already been on the way out, they are known to fail, but usually it is intermittent from heat soak.
You have done right in testing it by switching the coil packs though.
It probably won't help, but it would be worth a shot to remove the 3 coil packs, then the ICM, and check it all over for corrosion, if it has any carefully clean it with something line a wire brush, and or some fine sand paper, apply some dielectric grease, then put it back on.
If that does not work you could try a local salvage yard, but it may be better just to spend the money and get a new one, as you never know whether or not you'll be getting a good one or not.
A while back I found a spare one on E-Bay, it was not too expensive, I looked and don't see any on there at the moment though.
Wait, I think I just fond some, I see the best choice IMO which is an AC Delco one, and also a United Ignition Wire one, I have not heard of them though, so I'd go with the AC Delco one.
New Delphi Ignition Control Module D1977A | eBay
United Ignition Wire
New Ignition Control Module ICM for GM Vehicles Premium Quality | eBay
I know you may not want to go with one from E-Bay, but the guy selling it has pretty good feedback, so it may be worth it, you stand to save a good bit, that same ICM is like 187.00 on RockAuto, and 132.00 on Amazon.