Q: Car won't start, would not start with boost. Ran fine when I bought it. It sat for two weeks and the alarm was left on.

Hello. The short answer is yes - the alarm can drain the battery in 2 weeks. It is also possible that something else is draining the battery while the car is turned off, and all electrical systems should be passive. This problem can be diagnosed by connecting an ammeter to the positive (red) battery cable, observe the current drain, then one at a time, remove each fuse. Check to see if the current drain has dropped to near 0, then reinsert the fuse. This process should identify the faulty circuit in most cases. Further diagnosis is then required for the electrical components on that fuse to identify the component pulling current. A professional mechanic, like one from YourMechanic, can diagnose the starting problem and perform any procedures or repairs needed to have this resolved.