You could have water in it and the TheRandom1 is correct you should check all of them diffs are easy just stick your finger in and pull some fluid out you will see if it has water in them, I did the same to a Mazda tribute , just ended up replacing plugs (needed it) oil/air filter change and it started up, It had about 2qts of water in the oil pan and about 1 qt in the engine. I cranked it with the plugs out and shot the water out then used a small lenghth of clear tubing attached to my wet/dry vac and removed any left over. Toys fixed! = reason for blazer purchase wife got mad at me 4wheelin' the nice not paid for one!

Hopefully you will get it back running smooth