h2o in from above and behind the fuse box. leaving a large puddles on the driver’s side floor.
I had the same problem with a 2000 Blazer. I used a garden hose to pour water into the windshield cowling while looking under the dash with a flashlight. There was a split in the seam between the inner fender and the firewall letting the water in. The water was flowing down the seam under the carpet and coming back up through the carpet in the driver and passenger footwells. In your case, I would check the seam and look for any openings in the firewall where water could leak through.