Let'* try removing the ICM & Coil packs. Bring them inside & remove the coils. I want you to look for any signs of moisture & or corrosion. If possible leave them inside over night so any moisture will have a chance to evaporate. I saw a thread on another forum where the poster put the ICM in an oven for an hour to dry out. Car started after doing that. He just let the oven warm up to about 100 -120 degrees, turned off the oven & then put the ICM in. You could try that if you need the car ASAP. Clean up the ICM mounting plate before reinstalling ICM & Coils.
1999 Pontiac Bonneville SSEi (son'*)
1997 Chevy Lumina (daughter'*)
2006 Chevy Trailblazer (wife'*)
2006 Chevy Monte Carlo SS (Mine! -Zoom Zoom Zoom)