Short in brake system after 12v battery changed

Yea... We often call them Stealerships rather than dealerships... Their mechanics are specialists in warranty repair, not fixing older used cars. You need a hybrid mechanic that is going to find the least expensive fix. Could be as easy as a changing out a wire or sensor.

And if it's more complex component than that the best way to go about fixing such an old car is buying a used component from a wrecking yard because the dealership will charge more than the value of the car for a new versions of complex parts.

Try contacting @TMR-JWAP who's near you. He's an honest person who will get it fixed correctly for lowest price possible...

 

My 2006 had red triangle of death parking issues with a "parking brake not engaged" warning on the screen, when the 12V battery is depleted. It goes away once the car is started.

Perhaps your battery is low on charge or the wrong type? (shooting in the dark here)

 

Tell us about the jump start on the 12 volt battery before you went to the parts store.

 

Replacing the 12v battery in a Gen 2 pretty much requires disconnecting and dismounting the brake back-up power supply/capacitor box. This is the rectangular black box just to the driver-side of the battery. I would start there and look to ensure it's been properly reconnected. Inspect the wire harness to make sure none of the wires have been pinched/crushed/broken, etc.