Hey gals and gents. I have an embarrassing situation here so please no laughing... Grand prix 3.8 2006

The car wouldn't start and so I boosted it, started on a dime. Left it on to maybe charge battery. After 15 minutes, disco the cables, shut car off and attempted to start it again. Nothing. The terminals were corroded so I cleaned them proper. Tried to boost again and completely brain farted and reversed the positive/negative. I know, let the comments flood in, I deserve it. Car has 515kms on it and I been driving and fixing it myself for 400kms. So this to me is extremely upsetting/embarrassing.

When attempting to boost the wrong way, the negative plug on my car staring a small fire bunch of sparks. It melted the post clamp through and through. I went out and bought 2 new terminal clamps and installed them, still nothing. I connected and trickle charge/car starter, and still nothing after 30 minutes.

I assumed the battery was done from the get go, so I went out and bought a new one. Connect the new one and still, no start. What I got was all lights on dash, everything lit up basically short of turning over. Then I try again, turning the key, and not even a light comes on. No power whatsoever. Even with new battery.

I checked most of the fuses, from the small 10/15 and 25'* to the Batt Main 1,2,3,4,to starter. All had continuity. But I don't exactly know how to test the bigger black/grey fuses with 4 pins.

I watched some videos and people are pointing to a fuse ( on different vehicles altogether) 80 amp+ and show you how it'* blown. I don't see any fuses in the box higher than 50amp? I also heard I may have blown the computer?

While I go through the 50 pages of posts here, maybe someone can lead me in the right direction? I took work off today to gitter done, and would appreciate any help I can get. If there'* more info needed, let me know.

Thank you for your time.

Connecting the battery cables to the wrong terminals sends power into the ground system, and can cause significant damage. There is no easy button here. Take into a qualified mechanic.

I agree. Have the car taken to a shop. This isn't something that can be fixed without a decent set of eyes and tools looking at it.

I third the notion, to the mechanic.

Your only hope would be that you blew a single major ground bus, or other fuse/relay/switch to kingdom come, and it failed before damage was done elsewhere, but if that is the case, it could be tracked down fairly competently by a good mechanic.

500+k miles is quite an accomplishment! I wouldn't start investing money in parts until you have a solid casualty list going. A 12 year old mid sized car with that many miles on it is probably better off replaced.

Unless this is Canadia and you are using those Canadometer things, in which case it is still a full life led by the car.

I agree with the guys above. That said, I'm not sure how easy it is for you to have a mechanic look at it so throwing some ideas out there.

Maybe the negative terminal to body ground got melted?

Maybe hot to the starter solenoid got melted?

Maybe the starter solenoid is locked up from attempting to apply backwards?

Some questions:

When it is key-out everything is off, right? (if yes, this is good)

. . . and does dome light work properly when you open/close doors and with the headlight switch? (if yes this indicates several good circuit paths including some amount of ground)

Do the headlights and driving lights come on with the switch? (if yes this indicates several good circuit paths including some amount of ground)

Do the hazard lights work? (if yes this indicates several good circuit paths including some amount of ground)

With key in ignition, turn to run (but not start). Do lights light up on dash as they should? (if yes this indicates several good circuit paths including some amount of ground, and also possibly some good telemetry and perhaps PCM still works to some degree, especially if the [check engine] light comes on)

Does the chime sound like normal? (if yes this indicates several good circuit paths including some amount of ground, and perhaps PCM still works to some degree)

Do the turn signals work? (if yes this indicates several good circuit paths including some amount of ground)

Thinking these answers could give you a good idea of what is not broken that you can get to easily.

Next: Stare at one of the dash alert lights that are on. Turn the key to [start] then release quickly. Did the light dim at all? If not then likely no power getting to the starter. Since it sounds like you didn't turn the key while jumped backwards this would likely not be the ignition switch, and would have a good chance of being the starter or wire towards the starter.

My $0.02 , hope it helps. Please let us know how it goes.

. . . and just thought of this: Ignition in [run] not [start], connect any kind of OBD2 reader to the OBD2 port and see if you can scan and interact with it. If you have something that can read telemetry see if it can read something that you can actually read such as coolant temperature. It should be within around twenty degrees of the air the car has been parked in for a while depending on where you are in the world.