2000 Oldsmobile Alero car not starting

Try the jump-start again, or charge the battery at a slow rate for an hour. If it's not cranking but it will with a jump-start, you may have not run the engine long enough the last time to charge the battery. Depending on how discharged it was, and for how long, it can take a good ten to fifteen minutes before it STARTS to take a charge. It takes time for the acid in it to become conductive and allow the battery to charge.

Once the engine is running, measure the battery voltage. It must between 13.75 and 14.75 volts. If that is okay, that means the second part of the test will be valid. That requires a professional load tester to measure full-load output current and "ripple" voltage. Tell me what you find for all of those values and I'll figure out where to go next, if necessary.