B4 legacy twin turbo 2000

Hi , new here and this is first post but just need some advice. My key fob decided yesterday it just didn't want to work anymore. The alarm kept on engaging and wouldn't turn off. I thought it maybe the battery (in the alarm), as it's the same battery I purchased the car with (second owner). But to no luck.. now I can't even start my car, I know it can't be the car battery as I bought this brand new after purchasing the vehicle. Is there anyway of starting this car so I can go and purchase a new fob? Oh, I have a 2000 Subaru B4 legacy T/T.