Subaru Problems? Ask a Mechanic for Answers ASAP
What exactly is the car doing when you try to start it?Does the engine crank at all?
If in fact the immobilizer is set you can't turn that off without the dealer scan tool. This would mean the key lost it's programming. I hate to say it but there isn't another answer. You will also need all the keys and the tags that come with the original set of keys so they can recode the keys.
If the engine isn't cranking at all, then I would try a jump start in case the battery itself is actually the issue, otherwise it's going to need to be towed.
I am sorry to give you bad news, but it's just not something you can resolve on your own. If you could, then thieves would be able to steal your car.
Interesting, you fixed it but don't know how. I suspect whatever happened the car wasn't immobilized. At least not with the factory system.
Glad you got it working though!