I got a 2012 Mazda 3i 2.0L. Let my friend borrow it and he drained the battery and it went dead. He jumped the car off, but reversed the leads and popped the main fuse on the battery terminal. Once I replaced that it didnt want to start, turned over and tried a couple of times, but then it started and ran for about 5 minutes. I hooked my Matco Tools scan tool up to the OBD2 to check it out, and as soon as it linked up, the car shut off and wouldn't start back up. My question here is, did the computer just get fried? Or is there something else I need to check into? Relays? Or anything else? I'm looking at such a ridiculous price for all kinds of stuff to change the computer, so how can I tell if that's it for sure, or what else can I eliminate before buying a computer. Thank you for who all puts in time and energy into this for me.

 

I think the first thing you need to do is eliminate the "friend".

Does the Matco scan tool work okay in other cars? If it works fine in other cars, then we can probably eliminate it as the cause of failure. And since you had the car running after the battery snafu, it sounds like the computer is okay. Can you use the Matco to get readings without the engine running? With the car in accessories mode? When the car was running, was the Check Engine light on?

Just trying to gather more information.