'97 Lumina LS (3.1L) won't start after hail

My 97' Lumina won't start at all. It recently hailed for the first time since I got the car (I live in Phoenix, AZ), and hail got way under the hood and into everything in there. The lights and radio come on perfectly, but when I try to start it, nothing happens except the headlights dim. A friend's neighbor said it was probably the positive battery cable after looking at it briefly, so I replaced that. After I replaced it, it started the next couple times. Later that night, I was stranded and it hasn't started since.

My check engine light is on, and Autozone says it is either my O2 Sensor or my catalytic converter. I don't know if those failing could cause this sort of problem, but I could be wrong.

Does anyone have any ideas? Just ask if you need more information.

I don't think that this is the cause of the 'no start' problem. It seems to me that either you have a short in the starting circuit or that the battery is low. Also, maybe some wires are corroded...

I had the battery checked at Autozone right away - no problem there.

I replaced the positive battery cable because it looked pretty corroded, but that only tricked me into thinking it was fixed.

How could I check for a short in the starting circuit?

Come on...I need some help! :)