2001 chevy blazer extreme wont start

The battery will serve to crank the engine, and indeed you do have to have at least half decent reference voltage to power the engine's processor at this time also. But I don't suspect the battery is your initial issue. Sure, you need to have a known good battery, but jumping it usually would work. A condition where the engine cranks but does not start is most often related to a lack of fuel at the engine or a lack of spark. Inappropriate air (too much / too little) can influence this, but usually the engine would at least stumble a bit. An exhaust restriction would do the same. Have someone inspect the engine performance to troubleshoot your concern.