once a battery is connected even if the key is not in the ignition, there is always power at certain points in your car. Connecting a battery backwards will not start your car, but it can and will fry the wires to your starter.
When you connect the battery backwards you can cause major damage. You can blow the alternator or its fusible link. You can destroy electronics, particularly the various computers - and these are not cheap.
Depending on the age of the vehicle you probably have shorted or grounded the electrical system causing fuse(s) to blow. Question was kind of broad may want to be more specific
When a car battery in connected to itself (i.e. You connect jumper cables onto a battery and then connect the other two connectors to each other), you create a continual circuit with the battery and nothing else. A similar effect is when you hold a 9 Volt battery to your tongue and you feel a small but continual "zap". Imagine this effect, but much greater. Sparks will appear when the connectors are first connected. Warning: Do not do this. This will damage your car battery. The only reason you should connect a car battery through jumper cables is to connect it to another car's battery in order to "jump" a car.
You connect the positive terminal first.
If you connect the terminals together with them unhooked from the battery and the engine off, yes that is also called a capacitive discharge.If you connect the terminals together with them unhooked from the battery and the engine off, yes that is also called a capacitive discharge.
You have some serious problems. Hooking up a battery backwards plays hell with the electronics. If you really want to keep the car you will probably have to replace a lot if not all the electronic control devices that manage your engine.
Car battery charges can check the damage done to the actual battery but to the entire car is another story
Connect the negative cable first.
Very Dangerous........it would be a dead short. andcouldcause a fire or explosion.
Turn it the other way.
As long as the cables are connected properly.